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,.  JALIFORNIA  STATE  MINING  BUREAU.  I 

i  A.  S.  COOPER,  State  Mineralogist. 


ULLETIN  No.  18. 


San  Francisco,  October,  1900. 


} 


TH  E 


lother  Lode  Region  of  California. 


By  W.  H.  STORMS,  E.M. 


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Published  uuder  the  Directioii  of  HENRY  T.  CtACtE,  Governor  of  the  State  of  California. 


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The  May  Rock,  Mariposa  County. 


Croppings  of  the  Eagle-Shawmut  Mine,  Tuolumne  County. 


CALIFORNIA  STATE  MINING  BUREAU. 


A.  S.  COOPER,  State  Mineralogist. 


P 


» 


BULLETIN  No.  18. 


San  Francisco,  October,  1900. 


THE 


Mother  Lode  Region  of  California. 


By  W.  H.  STORMS,  E.M. 


Published  under  the  Directiou  of  HENRY  T.  GAGE,  Governor  of  the  State  of  California. 


A     J.    JOHNSTON 


SACRAMENTO: 
,     :     :      :      :     superintendent  state  printing. 
1900. 
UNIVERSITY  OF  CALIFORNIA 


CONTENTS. 


LETTER  OF  TRANSMITTAL  -------  3 

INTRODUCTORY  -  --------       5-    r> 

GENERAL  GEOLOGY  OF  THE  GOLD  BELT  -  -  -  -  7-  u 

The  Schists  and  Metamokphic  Rocks  -  -  -  -  -8-13 

The  Alteration  of  Other  Massive  Rocks  -  -  -  .  i3_  14 

SEVERAL  DIVISIONS  OF  THE  GOLD  BELT       -  -  -  -  -14-26 

The  Central  Gold  Belt         -------  i5_  iq 

Classification  and  Description  of  Rocks     -----      16-  18 

The  Dolomitic  Vein     --------  19-  21 

The  East  Lode         -  -  -  -  -  -  -  -  -21-26 

METHODS  OP  MINING -  -  -  26-35 

Timbering  -         -  -  -  -  -  -  -  -  -29-31 

Filling       ----------  31-  32 

Drainage         -  -  -  -  -  -  -  -  -  -32-33 

Comparison  of  Steam  and  Cornish  Pumps  -  .  .  .  33.  35 

The  Diamond  Drill  --------  35 

THE  COST  OF  MINING         -  -  -  -     '      -  -  -  -  35-39 

Detailed  Cost  of  Mining  at  Mahoney  Mine  -  -  .  -  36 

Detailed  Cost  of  Milling   at  Mahoney  Mill  -  -  -  37 

Detailed  Cost  of  Mining  and  Milling   at  Gwin  Mine  -  -  38 

MINING  MACHINERY         -  -  - 39-40 

MINE  BELL  SIGNALS  - 40-42 

California  Code  of  Signals  ------  40-  42 

THE  MINES  OP  AMADOR  COUNTY 43-87 

THE  MINES  OP  EL  DORADO  COUNTY  -  -  -  -  -  88-89 

THE  MINES  OF  CALAVERAS  COUNTY     ------    100-127 

THE  MINES  OP  TUOLUMNE  COUNTY  -  .  .  -  -  128-141 

THE  MINES  OP  MARIPOSA  COUNTY -    142-147 

THE  MINES  OP  MADERA  COUNTY      ------         148-150 


LIST  OF  ILLUSTRATIONS. 


Fig.  .     P^«^- 

1.  Diagrams  illustrating  the  transition  from  jointing  to  schistose  structure  in 

Greenstones         ----------  10 

2.  Method  of  working  veins  in  swelling  ground               -           -           -           -           -  29 

3.  Separator  at  the  Zeila  slimes  plant              -           -           -           -           -           -  47 

4.  Zeila  canvas  plant,  Jackson          --------  48 

5.  Canvas  table,  Zeila  Mill          --------  48 

6.  Hydraulic  ejector  at  Zeila  slimes  plant             .-_---  49 

7.  Pointed  box  at  Zeila  slimes  plant     -------  50 

8.  Plan  of  Groom  distributor             --------  51 

9.  Manner  of  placing  machine-drill  holes,  Kennedy  shaft             -           -           -  54 

10.  Sketch  showing  strike  of  formation  at  Kennedy  shaft          -           -           -           -  55 

11.  Horizontal  section  showing  timbers  in  Kennedy  vertical  shaft            -           -  56 

12.  Vertical  section  showing  method  of  timbering  of  Kennedy  shaft             -           -  57 

13.  Vertical  geological  section  of  Argonaut-Kennedy  vein              -           .           .  59 

14.  Sketch  showing  strike  of  formation  at  new  Oneida  shaft     -           -           -           -  .60 

15.  Station  at  1900-foot  level  of  Oneida  Mine               .           -           .           _           -  61 

16.  Station  at  2000-foot  level  of  Oneida  Mine          ------  62 

17.  Geological  sketch,  Wildman  Mine    -------  65 

18.  Fault,  900-foot  level  of  the  Mahoney  Mine        ------  66 

19.  Sketch  of  vein  in  Wildman  Mine      -------  67 

20.  Slaty  cleavage  in  folded  strata  at  Sutter  Creek            -           -           -           -           -  67 

21.  Sketch  showing  strike  of  formation  at  vertical  shaft,  Wildman  Mine           -  68 

22.  Section  of  guides  and  divider  in  Wildman  shaft         -           -           -           -           -  69 

23.  Method  of  timbering  in  Wildman  shaft      ------  69 

24.  Screen  frame,  Wildman  Mill         .--_----  70 

25.  Old  style  of  screen  frame  at  Wildman  Mill            -----  71 

26.  Cross-section  of  Lincoln  Mine,  Sutter  Creek              -           -           -           -           -  73 

27.  Corrugated  chuck-block.  Keystone  Mill      ------  79 

28.  Method  of  timbering,  Gwin  Mine            -           -           -           -           -           -           -  101 

29.  Screen  frame  and  chuck-block  at  Gwin  Mill           -----  103 

30.  Geological  section  of  Sheep  Ranch  Mine           -           -           -           -           -           -  105 

31.  Geological  cross-section  near  San  Andreas,  Calaveras  County             -           -  106 

32.  Mill  screen,  Lightner  Mill,  Angels           -------  no 

33.  Chuck-block,  Lightner  Mill 110 

34.  Chlorination  vat,  Utica  Reduction  Works,  Angels      -----  nc 

35.  Fault  in  Pine  Tree  Mine,  Mariposa  County            -----  145 

36.  Cross-section  Rex  Mine,  Madera  County           -           -           -           -           -           -  148 

37.  Horizontal  section.  Rex  Mine,  Madera  County               -           -           -           -  149 


May  Rock,  Mariposa  County  .-._--  Frontispiece 

Croppings  of  the  Eagle-Shawraut  Mine,  Tuolumne  County  -  -     Frontispiece 

Oneida  ]Mine,  Amador  County  --------      61 

Central  Eureka  Mine,  Amador  County  -  -  -    .        -  -  -  61 

Mahoney  Mine,  Amador  County         --------      65 

Timbering  in  caving  ground,  Mahoney  Mine,  Amador  County        -  -  -  65 

Lincoln  Mine,  Amador  County  --------      73 

Bunker  Hill  Mine,  Amador  County  -------  73 

North  shaft  and  mill,  Utica  Mine,  Calaveras  County        -  -  -  -  -    113 

Keystone  Mine  and  Mill,  Amador  County  ------  113 

Croppings  of  the  Mariposa  Vein,  Mariposa  County  -  -.  -  -  -    145 

Croppings  of  the  Louisa  Mine,  Mariposa  County         -  -  -  -  -         145 


LETTER  OF  TRANSMITTAL. 


San  Francisco,  Cal.,  September  30,  1900. 

To  His  Excellency  Henry  T.  Gage,  Governor  of  the  State  of  California; 
The  Honorable  The  Board  of  Trustees  of  the  California 
State  Mining  Bureau;  and  Hon.  A.  S.  Cooper,  State  Mineralogist. 

Gentlemen:  I  have  the  honor  to  submit  herewith  the  report  of  my 
investigation  of  the  mines  of  the  Gold  Belt  in  El  Dorado,  Amador, 
Calaveras,  Tuolumne,  and  Mariposa  Counties  during  the  spring  and 
summer  of  1900.  I  regret  that  the  necessity  of  visiting  some  of  the 
northern  counties  of  the  State  during  June  and  July  made  it  impossible 
to  complete  the  work  during  the  season,  but,  as  it  is  a  field  of  active 
operation,  the  coming  year  will  find  development  further  advanced,  and 
at  that  time  the  investigation  may  be  continued  with  more  satisfactory 
results  than  would  have  been  obtained  had  the  work  been  done  the  past 
season.  Very  few  other  than  operating  mines  were  visited,  and  of  these 
the  description  in  this  bulletin  is  limited  to  the  most  important  ones, 
the  others  appearing  in  a  general  report  which  shortly  follows  this 
bulletin. 

I  find  among  the  more  progressive  superintendents  and  mine  managers 
a  disposition  to  experiment  with  a  view  to  improving  mining  methods 
and  to  decreasing  the  expense  of  treating  ore,  and  as  a  result  we  find 
not  a  few  innovations  which  in  most  cases  will  be  adopted  in  general 
practice,  with  such  further  improvements  as  additional  experience  may 
suggest. 

It  affords  me  great  pleasure  to  state  that  the  mine  owners,  managers, 

and  superintendents,  almost  without  exception,  spared  neither  time  nor 

trouble  in  affording  every  facility  for  investigation  of  the  mines  under 

their  direction,  which  made  the  task  not  only  light,  but  pleasant. 

I  am,  yours  respectfully, 

W.  H.  STORMS. 


THE  MOTHER  LODE  REGION  OF  CALIFORNIA. 


By  W.  H.  storms,  E.M. 


4 


The  California  Gold  Belt  has  furnished  a  most  interesting  field  for 
geological  research  ever  since  its  discovery  in  1849.  It  has  received  the 
attention  of  many  geologists,  and  a  great  deal  has  already  been  pub- 
lished concerning  it.  Among  the  most  noted  and  valuable  of  these  con- 
tributions to  our  knowledge  of  the  Gold  Belt  are  the  early  writings  of 
Dr.  Rossiter  "W.  Raymond  and  Ross  E.  Browne,  and  more  recently  those 
of  H.  W.  Fairbanks  and  Ross  Browne,  and  the  exhaustive  maps  and 
reports  of  the  United  States  Geological  Survey.  The  various  reports  of 
the  State  Mining  Bureau  have  also  furnished  a  large  amount  of  valuable 
technical  and  statistical  information  on  the  subject. 

In  consideration  of  the  very  large  amount  of  descriptive  matter 
already  published  concerning  the  mines  of  the  Gold  Belt,  or  Mother 
Lode,  it  was  with  the  feeling  that  the  subject  was  worn  somewhat  thread- 
bare that  the  writer  undertook  the  re-investigation  of  this  important 
mining  field  in  January,  1900. 

Since  the  publication  of  the  Xlllth  report  of  the  State  Mineralogist 
in  1896,  no  publication  has  been  issued  by  the  State  regarding  the 
progress  of  work  in  the  counties  along  the  Gold  Belt,  though  this  period 
has  been  one  of  unusual  activity  and  progress  and  also  of  innovation  in 
these  mines.  Old  methods  have  in  many  cases  given  place  to  more 
modern  ideas,  and  still  more  radical  changes  may  be  anticipated  in  the 
near  future. 

An  era  of  deep  mining  has  commenced  which  can  only  be  carried  to 
the  greatest  success  by  the  adoption  of  modern  mining  methods  and 
improved  machinery,  together  with  a  closer  attention  to  the  economical 
treatment  of  the  ores.  Already  it  has  been  shown  that  mines  which 
were  worked  in  former  years  under  disadvantages  and  at  an  expense 
considerably  above  that  now  necessary  to  accomplish  given  results, 
after  years  of  idleness,  upon  being  reopened  and  equipped  with  modern 
machinery,  can  again  be  made  to  yield  a  handsome  profit,  where 
formerly  some  of  them  were  worked  at  a  loss. 

This  has  been  made  possible  by  the  reduced  cost  of  labor  in  later 
years;  by  the  superior  efficiency  of  nitro  powders  over  the  black  blast- 


6  CALIFORNIA   STATE   MINING    BUREAU. 

ing  powders  used  formerly  in  all  mining  operations  in  this  State;  by- 
better  and  cheaper  mining  supplies  of  all  kinds;  and  in  no  small 
degree,  by  improved  hoisting,  pumping,  and  milling  machinery,  and  to 
some  extent  also  by  improved  mining  methods. 

There  is  little  doubt  that  the  marked  mechanical  success  attending 
very  deep  mining  elsewhere,  notably  in  the  Lake  Superior  copper  mines 
and  in  the  gold  mines  of  South  Africa,  has  proven  a  great  incentive  to 
the  miners  of  California  to  emulate,  in  a  measure  at  least,  these  splen- 
did efforts,  and  we  now  find  large  vertical  shafts  being  sunk  to  a  depth 
far  exceeding  anything  heretofore  attempted  in  California  mines. 

There  are  mines  in  Amador  and  Nevada  Counties  now  operating  to  a 
depth  of  2500  feet  or  more  through  old  inclined  shafts,  usually  sunk  to 
conform  to  the  dip  of  the  vein,  or  approximating  it,  and  there  are  numer- 
ous mines  in  several  mining  counties  where  inclined  shafts  are  down 
1500  to  2000  feet.  The  managers  of  these  properties  realize  the  impor- 
tance of  having  shafts  sunk  at  a  uniform  angle — whether  vertical  or 
inclined — thoroughly  equipped  and  provided  with  the  best  hoisting 
machinery  in  order  to  reduce  the  cost  of  mining  to  a  minimum,  for  in 
nearly  all  of  the  large  mines  it  is  known  that  there  are  immense  bodies 
of  low-grade  ore,  too  poor  to  pay  when  worked  by  old  methods,  but  which 
would  afford  a  good  profit  if  mined  by  modern  methods  and  with  well- 
equipped  shafts  and  machinery  of  proper  construction.  This  matter 
will  be  more  fully  discussed  under  the  title  of  "  Methods  of  Mining." 

The  introduction  of  extensive  slimes  plants,  and  the  successful  opera- 
tion of  the  cyanide  process  in  its  various  forms,  have  also  contributed 
in  a  measure  to  increased  financial  success,  and  electric  plants  have 
also  been  installed  at  several  points  for  the  distribution  of  power  to 
mines  along  the  Gold  Belt.  These  installations  are  said  to  be  success- 
ful financially  as  well  as  mechanically.  Transmission  of  power  through 
the  medium  of  compressed  air,  though  not  an  innovation,  is  more  exten- 
sively employed  than  formerly. 


THE    MOTHER   LODE    REGION — GENERAL   GEOLOGY. 


GENERAL  GEOLOGY  OF  THE  GOLD  BELT. 

Owing  to  the  extremely  complicated  structural  geology  of  the  Cali- 
fornia Gold  Belt,  positive  assertions  as  to  the  relative  age  of  the  intru- 
sive rocks  which  so  commonly  occur  throughout  its  length  are  generally 
unsafe,  but  in  a  general  way  it  may  be  stated  that,  upon  rocks  of  an 
uncertain  but  very  great  age,  possibly  Archaean,  there  was  laid  down  in 
Palaeozoic  time  a  deep  series  of  sediments  consisting  of  mud,  sand, 
finely  comminuted  calcareous  fragments,  calcareous  ooze,  etc.  Follow- 
ing this  there  was  evidently  a  long  period  of  volcanic  activity,  during 
which  there  was  accumulated  a  vast  quantity  of  basic  rocks,  chiefly 
diorite  and  diabase,  and  basic  tuffs  and  breccias.  These  rocks  are 
mineralogically  closely  allied  to  the  andesites,  and  are  called  the  old 
andesites  by  the  United  States  Geological  Survey.  The  underlying 
formations,  together  with  the  tuffs,  were  consolidated  into  rock;  the 
mud  being  transformed  into  shale,  and  by  further  process  of  meta- 
morphism,  into  slate,  the  sand  becoming  quartzite,  and  the  calcareous 
material,  limestone. 

There  were  evidently  successive  periods  of  elevation  and  subsidence 
also,  resulting  in  the  formation  of  extensive  beds  of  conglomerate  along 
the  shore  lines.  During  the  Jurassic  age  there  was  deposited  upon  these 
older  formations  a  stratum  of  fragmentary  material  consisting  of  fine 
silt  and  sand,  forming  eventually  thick  beds  of  shale  and  sandstone. 

During  a  portion  of  this  period  volcanic  activity  was  again  pro- 
nounced, particularly  about  the  close  of  the  period,  during  which  there 
was  again  accumulated  a  large  amount  of  diabase  tuffs  and  breccias. 
In  some  localities  the  mud  deposits  and  the  tuffs  are  found  interbedded, 
showing  that  the  volcanic  outbursts  were  intermittent.  In  some  cases 
a  sandstone  is  found  wholly  made  up  of  diabase  material,  and  this  is 
probably  the  result  of  the  disintegration  of  some  previously  erupted 
material,  which  was  carried  down  from  an  elevated  ridge  and  deposited 
in  the  bed  of  the  sea.  These  sediments  have  subsequently  been  uplifted, 
folded,  crushed,  and  faulted.  The  dynamic  forces  were  still  at  work, 
and  large  dike-like  masses  of  diabase,  diorite,  serpentine,  and  other 
intrusive  rocks  were  thrust  from  below  into  the  complex  of  older  rocks. 

The  Palaeozoic  rocks,  owing  to  their  large  development  in  Calaveras 
County,  have  been  named  the  Calaveras  formation,  and  the  later  deposits 
of  Jurassic  age  have  been  called  the  Mariposa  beds  (as  this  formation 
is  most  extensively  exposed  in  Mariposa  County),  and  it  is  in  more  or 
less  close  association  with  these  beds  that  the  so-called  Mother  Lode  of 
California  occurs. 

Lying  to  the  eastward  of  the  above  described  formations  is  found  a 
broad  expanse  of  intrusive  rock,  which,  owing  to  its  peculiar  mineral- 


8  CALIFORNIA    STATE    MINING    BUREAU. 

ogical  character,  has  been  named  grano-diorite.  At  numerous  points 
along  the  contact  of  the  grano-diorite  with  the  formations  heretofore 
mentioned  there  is  found  abundant  evidence  that  the  grano-diorite  was 
intruded  later  than  the  greenstones,  and  it  is  also  later  than  the  Mari- 
posa beds.  There  is  some  reason  to  believe  that  the  grano-diorite  is  as 
late  as  the  Cretaceous. 

The  Mariposa  beds  appear  generally  to  occupy  a  position  along  the 
trough  of  a  synclinal  fold,  the  Calaveras  formation  being  found  both  to 
the  eastward  and  westward  of  the  Mariposa  beds.  The  occurrence  of 
the  diabase  tuffs  and  the  intrusion  of  great  masses  of  basic  dike  rock 
(diabase  and  diorite)  have  rendered  the  positions  of  the  Mariposa  beds 
and  the  Calaveras  formation  very  irregular  and  often  extremely  puz- 
zling, as  the  distribution  of  the  tuffs,  breccias,  and  intruded  dikes  is 
most  erratic.  It  is  more  than  probable  that  a  cross-section  taken  every 
half,  or  even  every  quarter  mile  along  the  Gold  Belt,  would  show  an 
entirely  different  structural  condition. 

The  Schists  and  Metamorphic  Rocks. — The  tremendous  compressive 
stress  to  which  these  rocks  have  been  subjected  since  their  uplift,  has 
resulted  in  the  formation  of  a  series  of  highly  crystalline  metamorphic 
rocks — the  mud  being  altered  into  slates,  the  sandstones  changed  to 
quartzite,  and  not  infrequently  the  limestones  are  found  altered  to 
marble.  The  greenstones  have  likewise  been  changed  over  broad  areas. 
The  pressure  and  movement  accompanying  it  have  resulted  in  many 
cases  in  a  complete  obliteration  of  the  original  character  of  the  normal 
rocks,  and  in  place  of  the  crystalline  granular  greenstones  we  find 
schists  and  slates  (the  amphibolite  schist  of  the  United  States  Geolog- 
ical Survey).  Throughout  the  entire  length  of  the  Gold  Belt  are  found 
greenstones  of  greatly  varying  texture  (chiefly  diabase),  which  have 
suffered  little  or  no  alteration. 

These  masses  of  greenstone  are  from  a  few  feet  to  several  hundred 
feet  in  width,  and  it  seems  not  improbable  that  they  were  mostly  intru- 
ded since  the  formation  of  the  schists.  In  some  instances  this  is  posi- 
tively known  to  be  the  case,  as  they  are  found  cutting  the  schists  in 
strike  and  dip.  In  some  of  the  gold  mines  these  greenstone  dikes  may 
also  be  clearly  seen  to  be  more  recent  than  the  inclosing  rocks,  and 
occasionally  they  are  found  intersecting  the  quartz  veins. 

Instances  may  be  observed,  however,  where  only  portions  of  certain 
massive  formations  are  schistose,  and  this  can  only  be  attributed  to  the 
local  effect  of  the  dynamic  forces  similar  in  character  to  those  which 
produced  the  original  metamorphism  of  the  older  formations.  The  gen- 
eral features  of  the  schistose  greenstones  (both  massive  and  tufaceous) 
occurring  in  California  are  so  similar  physically  to  those  of  the  Mar- 
quette and  Menominee  regions  of  Michigan  that  there  seems  no  room  to 


THE   MOTHER   LODE    REGION — GENERAL   GEOLOGY.  9 

doubt  that  in  each  case  similar  causes  operated  to  produce  like  effects. 
The  Michigan  region  has  been  studied  with  great  care  by  several  of  the 
best  geologists  of  America.  Those  interesting  rocks  and  the  manner  of 
their  formation  have  been  fully  described  by  G.  H.  Williams,  and  a  few 
extracts  are  taken  from  his  excellent  contribution  to  this  important 
subject,  the  dynamic  metamorphism  of  eruptive  rocks,*  for  the  reason 
that  they  apply  so  perfectly  to  the  conditions  found  in  California  along 
the  Gold  Belt,  and  I  have  not  the  slightest  doubt  that  greenstone  schists, 
wherever  found,  whether  as  the  result  of  the  alteration  of  massive  green- 
stone tuffs  or  of  fragmental  rocks  (sandstones),  derived  from  the  degra- 
dation of  older  greenstones,  are  the  direct  result  of  the  causes  ascribed 
by  Mr.  Williams  as  having  produced  the  schists  of  the  Michigan  region. 
In  referring  to  the  value  of  the  microscope  in  the  study  of  metamor- 
phism of  rocks,  Mr.  Williams  says: 

The  most  important  problems  presented  by  an  unaltered  massive  or  igneous  rock 
relate  to  (1)  its  chemical  composition,  and  (2)  to  the  conditions  under  which  it  was 
formed.  The  composition  expresses  itself  in  a  general  way,  in  the  nature  of  the  com- 
ponent minerals,  while  physical  conditions  attendant  upon  the  formation  of  the  rock 
may  be  traced  in  its  structure.  Each  of  these  has  therefore  been,  in  turn,  the  particular 
object  aimed  at  during  the  first  two  periods  of  petrographical  research. 

But  if  petrography  were  able  to  solve  satisfactorily  all  the  problems  presented  by  the 
unaltered  maSsive  rocks,  it  would  even  then  be  prepared  only  to  commence  its  most 
difficult  and  most  important  mission.  Rocks  are  in  reality  far  from  being  dead,  inert, 
stationary  masses,  which  they  appear  to  the  ordinary  observer.  The  fascinating  study 
of  chemical  geology,  especially  when  aided  by  the  microscope,  shows  them  to  be  in  a 
state  of  almost  constant  change.  It  is  true  that  some  of  the  oldest  rocks  seem  to  have 
suffered  hardly  any  alteration  since  they  were  first  formed,  but  most  of  them  are  ever- 
active  laboratories  where  old  products  are  being  pulled  to  pieces  and  new  ones  built  up. 
The  tracing-out  of  such  changes  is  an  important  aim  of  petrography  in  its  present  stage. 

In  the  study  of  the  structural  geology  of  the  California  Gold  Belt,  it 
was  found  necessary  to  employ  the  microscope,  and  the  conclusions 
reached  in  this  study  are  identical  with  those  submitted  by  Mr.  Williams. 
Upon  his  study  in  the  Michigan  area,  continuing,  he  says: 

There  are  two  distinct  kinds  of  alterations  which  take  place  in  a  solid  rock  mass, 
dependent,  of  course,  on  the  nature  of  the  changed  physical  conditions.    These  are: 

(1)  Metamorphism ;  or  the  passage,  under  circumstances  of  high  temperature  or 
pressure,  or  both,  of  less  crystalline  into  more  crystalline  compounds ;  or  the  change  of 
minerals  into  others  not  less  crystalline  or  insoluble  than  themselves. 

(2)  Decomposition  or  weathering ;  the  passage,  under  ordinary  atmospheric  condi- 
tions, of  crystalline  rock  constituents  into  compounds  less  crystalline  and  more  soluble 
than  themselves.    This  is  accomplished  generally  by  hydration  or  carbonization. 

Both  of  these  processes  are  frequently  seen  to  have  gone  on  in  succession  in  the  same 
rock  mass,  the  latter  more  or  less  completely  effacing  the  effects  of  the  former.  While 
distinct,  both  processes  agree  in  being  atomic  and  molecular  rearrangements  in  a  solid 
mass,  necessitated  by  some  change  in  external  conditions.  The  differences  in  these 
conditions,  however,  produce  widely  different  results ;  and  all  of  these  again  are 
essentially  different  from  those  produced  by  the  solidification  of  a  liquid  magma. 

The  student  of  the  crystalline  rocks  can  distinguish,  in  a  general  way,  four  classes  of 

*  Bulletin  No.  62,  United  States  Geological  Survey.  "The  Greenstone  Schist  area  of  the 
Menominee  and  Marquette  regions  of  Michigan." 


10 


CALIFORNIA   STATE    MINING   BUREAU. 


constituent  minerals,  and  this  is  true  in  spite  of  the  fact  that  the  same  species  niay  be 
represented  in  two  or  more  of  these  classes : 

(1)  Original  minerals  of  the  acid  rocks,  formed  by  the  solidification  of  a  magma  in 
a  state  of  aqueo-igneous  fusion  or  by  the  aid  of  mineralizers ;  e.  g.,  quartz,  orthoclase, 
mica,  zircon,  etc. 


\MMMMMll 

\\mmiW^'^^'^^ 

m 

wlm  M\i\\i 

■ 

1 

Wm 

wmmm 

1 

1 

DiAGtf\Ai^s  'illusiratii9§-|1=)e-rrahsi+-ioi7  h'oir)  joil^fing 
tbschistose  sti'uctures  in  the  gre  en  stones. 

Fig.  1. 

(2)  Original  minerals  of  the  basic  rocks,  formed  from  a  state  of  dry  fusion ;  e.  g., 
plagioclase,  augite,  olivine,  etc. 

(3)  Metamorphic  minerals,  formed  as  above  explained,  from  originals;  e.  g.,  horn- 
blende, albite,  biotite,  zoisite,  garnet,  staurolite,  andalusite,  etc. 

(4)  Decomposition  minerals;  e.  g.,  chlorite,  quartz,  carbonates,  hydroxides,  etc.  *  * 


THE    MOTHER    LODE    REGION — GENERAL    GEOLOGY.  11 

Rocks  may  be  altered  by  simple  pressure,  but  the  accumulated  strains  which  are 
generated  within  tliem  are  relieved  and  adjusted  by  overcoming  the  force  of  cohesion 
along  certain  planes.  Here  there  will  be  a  shearing  motion  of  greater  or  less  extent, 
and  a  consequent  crushing  of  the  rock.  The  rent  is  soon  healed  by  the  crystallization 
of  new  compounds  which  cement  the  crushed  fragments,  and  in  this  way  a  schistose 
band,  of  width  varying  with  the  intensity  of  the  force,  may  be  developed  in  the  midst 
of  an  otherwise  solid  and  massive  rock ;  or  a  number  of  such  bands  may  be  formed 
parallel  to  one  another  and  together  imparting  to  the  rock  the  appearance  of  a  foliated 
or  even  a  banded  schist. 

Conclusive  proof  of  this  process  might  be  difficult  to  discover  without  the  aid  of  a 
microscope,  but  this  instrument  is  happily  able  to  afford  sufficient  evidence  to  overcome 
all  doubt.    *    *    * 

The  first  step  toward  the  formation  of  a  schistose  structure  in  Twin  Falls  green- 
stones (and  this  is  hardly  ever  absent)  is  the  division  of  the  massive  rock  by  two 
systems  of  joints,  which  stand  about  perpendicular  to  the  surface  and  intersect  at  a 
varying  but  acute  angle.  These  joint  systems  divide  the  mass  into  diamond-shaped  or 
rhomboidal  prisms,  the  cross-sections  of  which  are  well  displayed  upon  the  frequent 
smoothly  glaciated  surfaces  of  the  rock.  The  appearance  of  such  a  siirface  is  diagram- 
matically  represented  in  Fig.  1. 

As  we  approach  the  schistose  band  in  the  massive  rock  these  interlacing  rhombs 
become  lengthened  out  more  and  more  by  an  approximation  to  parallelism  between 
the  two  systems  of  joint  planes. 

These  elongated  prisms  finally  become  very  much  extended  lenses,  which  interlock 
and  produce  a  well-developed,  wavy,  or  even  parallel  schistose  structure.  The  almost 
slaty  rocks  thus  produced,  especially  as  seen  at  Lower  Twin  Falls,  have  a  tendency  to 
break,  not  so  much  along  a  definite  plane,  as  parallel  to  a  line — i.  e.,  the  direction, 
normal  to  the  surface,  parallel  to  which  the  original  joint  planes  ran.  It  is  difficult  to 
obtain  well-shaped  hand-specimens  of  these  rocks,  but  narrow  rhombic  prisms  of 
almost  any  angle  are  easily  procured.  There  is  an  almost  equal  tendency  to  cleave 
along  any  plane  which  is  parallel  to  the  longest  axis  of  these  prisms. 

If  the  prisms  due  to  the  original  joint  planes  were  subjected  to  a  lateral  pressure 
which  developed  in  them  a  cleavage  that  successively  approached  more  and  more  nearly 
to  the  long  axis  as  the  prism  was  lengthened,  this  peculiar  tendency  to  separate  along 
a  line  rather  than  along  a  plane  is  precisely  the  structure  which  we  might  suppose 
would  result. 

The  strike  of  these  schistose  bands  follows  the  direction  which  bisects  the  acute 
angle  of  the  rhombic  prisms.  This  is  for  the  most  part  from  S.  70°  to  80°  E. ;  agreeing 
with  the  prevailing  strike  of  all  the  rocks  in  this  system.  There  are,  however,  many 
exceptions  where  these  schistose  bands,  even  where  near  together,  follow  different 
directions  ;  for  instance,  I  observed  in  the  massive  though  jointed  rock  on  the  Michigan 
side  of  Upper  Twin  Falls,  two  schistose  chloritic  bands  quite  near  together,  one  having 
a  strike  N.  180°  E.,  and  the  other  S.  73°  E.,  while  the  dip  of  each  was  nearly  vertical. 
Such  cases  are  easily  explicable  on  the  supposition  that  these  bands  were  produced  by 
mechanical  agencies,  but  it  is  quite  impossible  to  reconcile  them  with  the  supposition 
that  these  bands  are  in  any  way  the  result  of  sedimentation. 

It  is  not  infrequently  noticed  that  there  is  a  local  development  of 
schistose  structure  of  massive  rocks  in  the  immediate  neighborhood  of 
fissures  and  veins.  A  typical  instance  of  this  character  may  be  observed 
on  Wood's  Creek,  a  few  hundred  feet  below  the  pumping-station,  near 
the  Bonanza  Mine  at  Sonora,  in  Tuolumne  County.  Here  a  quartz 
vein,  about  twelve  inches  in  width,  traverses  a  hard,  dark-green  diorite. 
The  walls  on  either  side  are  altered  for  a  width  of  three  to  five  feet, 
being  soft  talcose  or  chloritic  schist  near  the  vein,  and  passing  over  by 
transition  to  the  normal  diorite.  These  occurrences  are  not  at  all 
uncommon,  though  often  of  local  character. 


12  CALIFORNIA   STATE    MINING   BUREAU. 

In  Amador  and  Calaveras  Counties,  and  also  to  some  extent  in 
El  Dorado  County,  I  found  peculiar  banded  schists,  which  have  attracted 
the  attention  of  many  geologists.  Similar  banded  schists  occur  in  the 
Michigan  area,  above  referred  to,  of  which  Mr.  Williams  speaks  as 
follows: 

The  banded  greenstone  schists  which  form  the  prevailing  rock  over  the  northern  por- 
tion of  the  Marquette  area,  have  been  regarded  by  all  geologists  who  have  ever  studied 
them,  as  originally  sedimentary  deposits,  and  repeated  examination  of  them  in  the  field 
seems  incapable  of  leading  to  any  other  conclusion.  They  are  everywhere  stratified 
witn  the  greatest  regularity  in  bands  of  lighter  and  darker  shades  of  green.  This 
structure  is  to  be  most  advantageously  seen  in  the  woods  just  north  of  Marquette  and 
near  Lighthouse  Point.  Here  glaciated  areas  of  considerable  extent  often  show  a  finely 
ribboned  appearance,  looking  as  though  the  sharp  parallel  lines  had  been  drawn  with  a 
ruler.  The  alternation  in  the  composition  of  the  layers  is  so  frequent  and  so  constant) 
and  their  parallelism  to  the  east  and  west  strike  of  all  the  rocks  in  this  neighborhood  is 
so  exact,  that  no  hypothesis  of  their  originally  massive  character  will  satisfactorily 
account  for  the  observed  facts.    *    *    * 

On  tlie  other  hand,  their  chemical  as  well  as  their  mineralogical  composition  renders 
it  impossible  to  separate  them  from  the  massive  and  highly  altered  greenstones  (uralite 
diabases,  etc.),  with  whicli  they  are  most  intimately  associated.  Their  parallel  banding 
indicates  a  fragmental,  but  their  chemical  and  their  mineral  composition  indicate  an 
igneous,  origin.  The  only  satisfactory  reconciliation  of  these  opposite  sets  of  characters 
is  to  be  found  in  that  group  of  rocks  intermediate  between  sediments  and  lavas, 
known  as  volcanic  tuffs. 

In  the  opinion  of  the  writer,  then,  the  banded  greenstone  schists  of  the  northern  Mar- 
quette area  are  to  be  regarded  as  consolidated  and  highly  metamorphosed  diabase  tuffs. 
These  are  intimately  associated  with  the  numerous  contemporaneous  flows  of  diabase 
and  quartz  porphyry,  together  with  the  tuffs  of  the  latter  rock;  while  all  have  been 
broken  through  by  much  younger  dikes,  both  basic  and  acidic. 

*******  -Si-**** 

In  order  to  obtain  a  clear  idea  of  just  how  these  ancient  and  much  disguised  tuffs 
acquired  their  present  form  and  apparently  dual  character,  it  will  be  advantageous  to 
ascertain  what  is  known  of  analogous  formations  of  comparatively  recent  date.  Captain 
C.  E.  Dutton's  descriptions  of  the  fragmental  rocks  accompanying  the  Tertiary  erupt- 
ives  of  the  high  plateaus  of  Utah  are  well  suited  to  this  purpose.  He  says,  in  speaking 
of  the  extent  of  these  deposits : 

"Some  of  the  mostinterestinglithological  problems  presented  by  the  volcanic  products 
of  the  high  plateaus  are  those  relating  to  the  origin  and  development  of  what  may  be 
termed  the  clastic  igneous  rocks,  or  rocks  apparently  composed  of  fragmental  materials 
of  igneous  or  volcanic  origin,  but  now  stratified  either  as  so-called  tufaceous  deposits  or 
as  conglomerates.  These  are  exceedingly  abundant  in  all  of  the  great  volcanic  districts 
of  the  world,  and  often  enormously  voluminous. 

"  How  those  of  the  high  plateaus  would  compare,  in  respect  to  magnitude,  with  those 
of  other  regions,  I  do  not  accurately  know,  but  absolutely  their  bulk  is  a  source  of  utter 
astonishment.  They  cover  nearly  2000  square  miles  of  area,  and  their  thickness  ranges 
from  a  few  hundred  feet  to  nearly  2500  feet,  the  average  being  probably  more  than  1200 
feet.  Lavas  are  frequently  intercalated,  but  much  more  frequently  no  intercalary  lavas 
are  seen,  and  in  general  they  seldom  form  any  large  proportion  of  the  entire  bulk  when 
they  occur  in  conjunction  with  the  clastic  masses." 

Again,  in  speaking  of  the  peculiar  liability  of  such  deposits  to  metamorphism,  the 
same  writer  says: 

"  A  very  striking  characteristic  of  these  clastic  volcanic  rocks,  both  the  tufas  and 
the  conglomerates,  is  their  great  susceptibility  to  metamorphism.  Not  only  have  the 
beds  in  many  localities  been  thoroughly  consolidated,  but  they  have  undergone  crystal- 
lization. These  tufas  and  conglomerates,  which  are  of  older  date,  and  which  have  been 
buried  beneath  more  recent  accumulations  to  considerable  depths,  rarely  fail  to  show 


THE    MOTHEK    LODE    REGION — GENERAL    GEOLOGY.  13 

conspicuous  traces  of  alteration,  and  in  many  cases  have  been  so  profoundly  modified 
that  for  a  considerable  time  there  was  doubt  as  to  their  true  character. 

"The  general  tendency  of  this  process  is  to  convert  the  fragmental  strata  into  rocks 
having  a  petrographic  facies  and  texture  very  closely  resembling  certain  groups  of  igne- 
ous rocks.  When  we  examine  the  rocks  in  situ,  no  doubt  can  exist  for  a  moment  that 
they  are  water-laid  strata.  The  hand-specimens  taken  from  the  beds,  which  are 
extremely  metamorphosed,  might  readily  pass,  even  with  close  inspection,  for  pieces  of 
massive  eruptive  rocks,  were  it  not  for  the  reason  that  the  original  fragments  are  still 
distinguishable,  partly  by  slight  differences  in  color,  partly  by  slight  differences  in  the 
degree  of  coarseness  of  texture.  But  the  matrix  has  become  very  similar  to  the  included 
fragments,  holding  the  same  kinds  of  crystals,  and  under  the  microscope  it  shows  a 
ground-mass  of  the  same  texture  and  composition." 

The  Alteration  of  Other  Massive  Rocks. — The  greenstones  are  not 
the  only  massive  rocks  which  have  undergone  a  more  or  less  complete 
alteration  in  the  region  of  the  Gold  Belt.  There  are  two  rocks  in  par- 
ticular to  which  I  wish  to  call  attention.  These  are  the  calcareous 
rocks  which  constitute  the  great  dolomitic  vein,  previously  referred  to, 
and  a  dark  green,  massive,  extremely  hard,  and  tough  rock  found  at 
numerous  places  along  the  Gold  Belt,  notably  in  Calaveras  County  just 
east  of  San  Andreas;  near  Dogtown,  three  miles  from  Angels;  at 
Smith's  Flat,  west  of  Angels,  and  elsewhere.  The  ankerite  or  dolomite 
vein  is  usually  distinguished  by  its  great  width  and  massive  character, 
and  the  occurrence  of  more  or  less  abundant  mariposite;  but  in  many 
places  we  find  this  hard,  thoroughly  crystalline  rock  has  been  com- 
pressed, sheared,  and  completely  altered,  passing  over  by  gradual  transi- 
tion to  typical  soft  talc  schist. 

A  series  of  transition  rocks  of  this  character  was  obtained  at  the 
Pacific  Mine,  Placerville,  El  Dorado  County,  and  is  on  exhibition  in  the 
Museum  of  the  State  Mining  Bureau  in  San  Francisco.  Similar 
occurrences  have  been  noted  in  a  score  of  mines,  from  Mariposa  County 
northward  as  far  as  Placerville,  but  collections  from  other  mines  have  not 
been  placed  upon  exhibition,  because  the  occurrence  is  essentially  the 
same  in  each  case,  and  the  space  available  in  the  Mining  Bureau  is 
already  crowded. 

Concerning  the  other  massive  rock,  hand-specimens  were  selected 
from  the  Ford  Mine  at  San  Andreas,  also  from  a  similar  occurrence  at 
the  Smyth  Mine  near  Angels,  and  slides  cut  for  microscopic  study. 
These  prove  the  rock  to  consist  of  a  matted  aggregate  of  minute  scales 
of  talc,  with  a  little  calcite  and  magnetite.  The  rock,  although  the 
freshest  obtainable,  is  very  evidently  not  in  its  normal  condition,  but  is 
an  igneous  rock  which  has  already  undergone  considerable  change.  It 
may  have  been  a  gabbro  or  some  allied  eruptive  rock,  which,  by  a 
process  of  compression  and  shearing  previously  described,  is  now  found 
changed  into  a  typical  massive  crystalline  granular  or  schistose 
steatite  (soapstone).  Undoubtedly,  the  alteration  of  massive  rocks  to  a 
schistose  or  slaty  condition  is  very  much  more  common  than  is  generally 


14  CALIFORNIA   STATE   MINING    BUREAU. 

supposed,  but  unfortunately  too  little  attention  had  been  given  in  the 
past  to  these  phenomena. 

It  has  been  noticed  in  several  instances  vi^here  mine  workings  have 
been  extended  into  the  steatite  masses,  that  not  infrequently  the  rock  is 
found  to  consist  of  a  coarsely  crystalline  aggregate  of  semi-schistose, 
calcareous  and  magnesian  minerals  and  to  greatly  resemble  the  partly 
altered  ankerite  and  dolomite  found  along  the  Central  Gold  Belt. 
Notable  instances  may  be  found  in  the  Ford  Mine  at  San  Andreas  in 
Calaveras  County,  and  at  the  Spanish  Mine  near  Forest  Hill  in  Placer 
County.  As  these  rocks  approach  so  nearly  the  dolomite  of  the  Central 
Gold  Belt,  they  may  be  considered  as  indicating  the  possible  origin  of 
the  dolomitic  veins  from  basic  eruptives. 


THE  SEVERAL  DIVISIONS  OF  THE  GOLD  BELT. 

Throughout  the  entire  length  of  the  great  synclinal  trough  of  the 
Gold  Belt  are  found  the  gold-bearing  veins  which  constitute  the  so-called 
Mother  Lode.  It  seems  unfortunate  that  the  name  was  ever  given 
to  this  portion  of  the  Gold  Belt,  as  it  conveys  to  the  minds  of  those 
unfamiliar  with  the  geological  structure  and  veins  of  the  region,  an 
impression  of  a  continuous,  unbroken  vein.  That  such  a  condition 
does  not  exist  is  well  known  to  those  familiar  with  these  mines. 

There  are  through  that  portion  of  the  State  occupied  by  the  counties 
extending  from  Mariposa  on  the  south  to  the  southern  portion  of  El 
Dorado  County  on  the  north,  at  least  four  distinctly  recognizable  gold 
belts  :  That  which  skirts  the  low  foothills  along  the  Great  Central  Val- 
ley includes  the  copper  deposits  found  at  and  near  Green  Mountain  in 
Mariposa  County,  and  southward  in  Madera  County,  those  at  Copper- 
opolis  and  at  Campo  Seco  in  Calaveras  County,  and  at  Ranlett  in 
Amador  County,  and  also  the  gold  mines  of  Salt  Spring  Valley  in 
Calaveras  County.  It  may  also  be  considered  as  embracing  the  gold 
mines  near  Hornitbs  in  Mariposa  County,  and  those  near  lone  in  Ama- 
dor County. 

East  of  this  a  distance  of  8  or  10  miles  is  found  the  most  important 
gold-bearing  belt  of  the  State,  which  has  received  the  name  of  "  Mother 
Lode."  This,  it  seems  to  me,  it  would  be  well  to  designate  as  the  Central 
Lode  of  the  Gold  Belt.  It  must  be  understood  and  remembered  in  this 
connection  that  the  gold-bearing  veins  are  nowhere  absolutely  continu- 
ous and  unbroken  for  a  great  distance,  but  that  the  so-called  lode  is 
frequently  interrupted  by  its  absolute  disappearance  for  considerable 
distances. 

Lying  east  of  the  Central  Lode,  in  Mariposa  County,  a  distance  of 
nearly   20  miles,  and  extending  in  a  northwesterly  direction,  nearly 


THE    MOTHER    LODE    REGION — THE   SEVERAL    DIVISIONS.  15 

parallel  with  the  Central  Lode,  and  passing  through  Tuolumne  and 
Calaveras  Counties,  is  the  third  gold-bearing  lode,  which  in  Amador 
County  has  approached  to  within  6  to  10  miles  of  the  Central  Lode. 
This  is  known  as  the  East  Lode,  and  embraces  many  interesting  and 
important  mines. 

Still  farther  eastward  lies  at  least  one  mineral  belt  which  has  been 
opened  at  several  points,  but  of  which  comparatively  little  is  known  as 
yet.     This  might  properly  be  named  the  Sierra  Lode. 

It  is  the  intention  to  fully  investigate  this  important  field  in  the 
future,  as  it  is  one  of  great  promise.  The  veins  are  large,  and  carry 
sulphides  of  iron,  lead,  zinc,  and  copper,  and  also  gold  and  silver. 

The  Central  Gold  Belt. — It  is  with  the  Central  Gold  Belt  we  have 
chiefly  to  deal  in  this  Bulletin,  as  lack  of  time  precluded  a  thorough 
investigation  the  past  season  of  the  entire  region  comprising  the  Gold 
Belt. 

For  years,  in  fact  since  its  early  history,  the  clay  slates  of  the  Mari- 
posa beds  have  been  considered  an  absolutely  essential  feature  and 
accompaniment  of  the  important  gold  mines  of  the  Central  Gold  Belt. 
The  veins  have  been  referred  to  as  "contact  veins,"  and  in  many  sec- 
tions the  immediate  contact,  or  close  proximity,  of  the  Mariposa  clay 
slates  has  been  deemed  indispensable  to  pay  rock. 

Such,  however,  is  apparently  not  the  case  in  Amador  County,  where 
a,re  situated  the  deepest  and  most  productive  mines.  While  it  is  possi- 
ble that  some  of  these  mines  are  confined  wholly  to  the  Mariposa  clay 
slates,  or  occur  at  contact  of  the  Mariposa  clay  slates  and  massive 
greenstones,  or  the  amphibolite  schists  resulting  from  their  alteration, 
if  such  be  the  case  the  instance  is  unknown  to  the  writer,  for  without 
exception,  the  large  number  of  accessible  mines  prove  that  the  Mariposa 
clay  slates  form  really  no  important  feature  as  related  to  ore  deposition, 
while  thus  far  in  Amador  County,  south  of  Plymouth,  all  development 
confined  to  the  typical  clay  slates  of  the  Mariposa  beds  has  proven  the 
fissures  in  that  formation  valueless,  and  these  developments  reach 
many  thousands  of  feet  of  shafts  and  drifts. 

The  fissures  in  which  the  ore  deposits  occur  along  the  Central  Lode, 
with  no  exception,  so  far  as  the  writer  is  aware,  cut  the  dip  and  usually, 
also,  the  strike  of  the  inclosing  rocks.  The  dip  of  the  slaty  and 
schistose  formations  is  uniformly  to  the  eastward,  though  at  greatly 
varying  angles,  but  usually  between  50  and  80  degrees,  while  the  dip  of 
the  vein  fissures  is  always  somewhat  less  in  approximately  the  same 
direction. 

In  the  mines  of  Amador  County  are  found  a  peculiar  black  slaty 
rock,  often  approaching  closely  in  physical  appearance  the  clay  slates  of 
the  Mariposa  beds.  They  may  usually  be  readily  distinguished  by  a 
peculiar  pitted  appearance.     This  feature  ranges  from  rather  coarse, 


16  CALIFORNIA   STATE    MINING   BUREAU. 

thickly  scattered,  knotty  granules,  to  the  fine  dots  resembling  pin 
pricks — the  finer  grained  and  the  more  slaty  in  structure  the  rock,  the 
finer  are  the  pits. 

For  years  these  rocks  have  not  been  distinguished  from  the  black 
clay  slates  of  the  Mariposa  beds,  but  the  writer  noticing  that  this 
peculiar  slaty  rock  was  of  persistent  occurrence  with  the  most  impor- 
tant ore-bodies  of  Amador  County,  determined  to  ascertain  if  possible 
what,  if  any,  difference  there  was  between  these  pitted  slates  and  the 
smooth,  satin-like  slates  of  the  Mariposa  beds.  With  this  object  in 
view,  several  series  of  rocks  were  collected  at  various  mines,  showing 
complete  transition  from  a  massive  or  slightly  schistose  rock  to  a  perfect 
black  slaty  rock,  the  specimen  always  showing  the  pits  as  above 
described,  and  being  obtained  from  certain  cross-cuts  where  the  transi- 
tion was  evident. 

These  rocks  were  placed  in  the  hands  of  H.  W.  Fairbanks,  of  Berke- 
ley, who  prepared  slides  and  carefully  studied  them  with  the  aid  of  the 
petrographical  microscope.  This  investigation  resulted  in  proving  that 
these  peculiar  slates  and  schists  were  the  result  of  the  shearing  and 
alteration  of  tuffs  (evidently  diabase),  and  that  the  rock  was  originally 
of  fragmentary  origin,  though  made  up  of  diabase  material  (augite, 
plagioclase,  etc.).  Their  character  is  rendered  perfectly  evident  under 
the  microscope,  and  the  change  from  one  phase  of  alteration  to  the  next 
may  be  clearly  traced  in  the  several  rock  sections. 

CLASSIFICATION  AND  DESCRIPTION  OF  ROCKS 
Collected  toy  W.  H.  Storms  along  Central  Gold  Belt. 
Determinations  made  by  H.  W.  Fairbanks,  A.B. 
Nos.  1  to  9,  inclusive,  From  cross-cut  900-level,  Keystone  Mine,  Amador  County. 

No.  10.  From  tunnel  east  of  Keystone  Mine,  Amador  County. 

No.  11.  From  tunnel  east  of  Keystone  Mine,  Amador  County. 

No.  12.  From  west  wall  of  Oneida  Mine,  Amador  County. 

No.  13.  From  west  wall  of  Oneida  Mine,  Amador  County. 

No.  14.  From  east  shaft  of  Kennedy  Mine,  Jackson,  Amador  County. 

No.  15.  From  east  shaft  of  Kennedy  Mine,  Jackson,  900-level,  Amador  County. 

No.  16.  From  hanging-wall  of  Bunker  Hill  Mine,  Amador  County. 

No.  17.  From  Baliol  Mine,  Sutter  Creek,  Amador  County. 

No.  18.  From  west  wall  of  Argonaut  Mine,  Amador  County. 

No.  19.  From  Carson  Creek,  Calaveras  County. 

No.  20.  From  dike  in  Copperopolis  Mine,  Calaveras  County. 

No.  21.  From  dike  in  Commodore  Mine,  San  Andreas,  Calaveras  County. 

No.  22.  From  Ford  Mine,  San  Andreas,  Calaveras  County. 

No.  23.  From  Ford  Mine,  San  Andreas,  Calaveras  County. 

No.  24.  From  Smyth  Mine,  Angels,  Calaveras  County. 

No.  25.  From  Smyth  Mine,  Angels,  Calaveras  County. 

No.  26.  From  Pocahontas  Mine,  Logtown,  El  Dorado  County. 

No.  27.  From  German  Mine,  El  Dorado  County. 

No.  28.  From  German  Mine,  El  Dorado  County. 

No.  29.  From  German  Mine,  El  Dorado  County. 

No.  30.  From  hill  north  of  Church-Union  Mine,  El  Dorado  County. 

No.  31.  From  hill  north  of  Church-Union  Mine,  El  Dorado  County. 

No.  32.  From  hill  north  of  Church-Union  Mine,  El  Dorado  County. 

No.  33.  From  hill  north  of  Church-Union  Mine,  El  Dorado  County. 


THE    MOTHER    LODE    REGION — THE    SEVERAL   DIVISIONS.  17 

Nos.  1  to  9,  inclusive,  are  from  the  900-foot  level  of  the  Keystone.  Some  of  these  have 
been  supposed  to  be  dikes,  but  Mr.  Storms  is  unable  to  tell  from  the  section  given  where 
the  igneous  rock  ends  and  the  supposed  slate  begins.  A  microscopic  study  of  these 
rocks  shows  that  in  all  probability  they  are  all  of  sedimentary  origin,  a  series  of  tuffs 
and  slate,  the  tuffs  being  fragmental  greenstones  or  diabases. 

No.  1.  This  rock  to  the  unaided  eye  has  every  appearance  of  being  a  dike.  Porphy- 
ritic  crystals  of  augite  are  embedded  in  a  tine  green  matrix.  Under  the  microscope 
this  rock  has  the  appearance  of  being  a  tuff.  The  constituents  are  badly  decomposed 
crj'stals  of  augite  and  cloudy  masses  of  feldspar  in  a  finely  granular  base.  Granular 
magnetite  is  present. 

No.  2.  To  the  eye  this  rock  clearly  betrays  its  tufaceous  character.  Its  components 
are  arranged  in  irregular  layers.  Under  the  microscope  the  tufaceous  character  is  also 
seen.  Augite  crystals,  granular  magnetite,  and  cloudy  tabular  areas  make  up  the  rock. 
A  large  part  of  the  matter  of  the  rock  is  indeterminable,  but  there  is  no  doubt  that  it  is 
a  diabase  tuff. 

No.  3.  In  the  hand-specimen,  this  rock  shows  its  clastic  origin  in  the  alternating 
layers  of  greenish  and  argillaceous  material.  The  green  is  probably  tufaceous,  and 
the  black  of  the  same  composition  as  the  slates.  Both  show  signs  of  metamorphism  in 
the  presence  of  a  pitted  surface  caused  by  little  crystals.  The  exact  nature  of  these 
could  not  be  determined,  but  in  all  these  slates  they  are  characteristic  of  metamorphic 
action.  Under  the  microscope  this  rock  does  not  show  clearly  its  origin.  It  might  be 
either  a  sedimentary  rock  or  an  altered  igneous  one.  It  is  made  up  of  ragged,  clear, 
and  cloudy  areas.  A  green  mineral  has  the  appearance  of  secondary  hornblende. 
There  are  some  augite  grains.    This  is  a  fine-grained  rock. 

Nos.  4,  5,  G,  7,  8,  and  9.  These  are  all  black  slate.  In  section  they  are  practically 
opaque.  In  some  there  are  little  crystals  with  clear  borders  and  dark  centers,  crystals 
produced  by  metamorphism. 

No.  10.  This  rock  might  be  taken  for  a  fine-gi'ained  eruptive  greenstone,  but  under 
the  microscope  it  has  much  the  appearance  of  being  a  fragmental  greenstone.  The 
rock  is  much  decomposed,  but  contains  a  large  amount  of  augite  and  considerable 
granular  iron  ore.  It  is  somewhat  schistose,  the  crystals  and  cloudy  masses  being 
arranged  along  parallel  lines.    It  is  quite  likely  a  fragmental  rock. 

No.  11.  Also  an  augitic  tuff.  The  rock  mass  is  made  up  largely  of  augite  crystals 
thickly  matted  together  with  cloudy  material  and  granular  magnetite.  The  cloudy 
material  in  these  tuffs  may  have  been  originally  the  mud  resulting  from  the  grinding 
up  of  diabase  fragments. 

No.  12.  This  is  an  augite  porphyrite,  generally  termed  diabase  or  greenstone.  The 
rock  is  much  decomposed ;  shows  prominent  crystals  of  augite,  but  the  feldspars  have 
almost  completely  disappeared  in  a  greenish,  cloudy  mass. 

No.  13.  Diabase  or  augite  porphyrite.  This  is  a  fresher  rock  than  the  last,  but  of 
the  same  general  cfharacter  originally.  It  contains  large  crystals  of  augite,  and  smaller 
ones  of  feldspar  in  a  cloudy  decomposed  ground-mass.    The  rock  is  somewhat  talcose. 

No.  14.  This  is  a  medium-grained  diabase.  Under  the  microscope  it  appears  to 
consist  largely  of  augite,  with  some  small  decomposed  crystals  of  feldspar  and  iron  ores. 

No.  15.  This  is  a  fine-grained  diabase  tuff,  and  quite  schistose.  It  is  made  up  of 
augite  grains,  and  faintly  polarizing  masses  are  arranged  in  layers  with  opaque  seams 
between  them. 

No.  16.  This  is  probably  a  greenstone  tuff.  It  contains  much  cloudy  matter,  augite 
crystals,  others  which  were  once  feldspar,  and  some  which  resemble  hypersthene.  Mag- 
netite scattered  through  the  rock. 

No.  17.  This  is  a  talcose  schist  derived  from  what  was  probablj'  a  fragmental  green- 
stone or  tuff.    The  body  of  the  rock  is  made  up  of  thickly  matted  rods  and  scales  of  talc. 

No.  18.  Coarse  diabase.  This  rock  contains  an  excess  of  augite  crystals  fairly  fresh 
in  character,  and  a  cloudy  base  in  which  outlines  of  feldspar  crystals  can  be  made  out. 
It  has  been  rendered  schistose  through  pressure. 

No.  19.    Layers  of  augitic  tuff  and  dark  slate.    Under  the  microscope  the  layers  are 
seen  to  be  made  up  of  cloudy  indeterminable  material,  through  which  are  scattered 
fragments  of  augite  crystals.    They  make  up  half  of  the  rock.    The  dark  bands  contain 
2 MB 


18  CALIFORNIA   STATE   MINING   BUREAU. 

less  augite  and  stringy  opaque  matter.  They  have  the  character  of  some  of  the  slates 
except  for  the  scattered  augite  fragments. 

No.  20.  In  the  hand-specimen,  Nos.  20  and  21  look  much  alike.  The  rocks  are  coarse 
grained,  with  their  dark  constitutents  altered  to  a  green  scaly  talcose  mineral.  They 
contain  much  feldspar  and  cubes  of  iron  pyrite.  Under  the  microscope  No.  20  is  seen 
to  consist  of  an  acid  plagioclase  feldspar,  perhaps  oligoclase,  quartz,  and  a  green 
mineral  replacing  hornblende,  also  magnetite.  This  is  a  much  decomposed  rock,  but 
might  be  termed  a  quartz  diorite. 

No.  21.  Under  the  microscope  this  rock  is  seen  to  consist  of  a  decomposed  feldspar 
similar  to  No.  20,  and  green  chloritic  matter  replacing  some  dark  silicate,  probably 
hornblende.    This  rock  is  also  a  diorite. 

No.  22.  This  is  a  massive  green  rock  made  up  of  an  aggregate  of  fine  talcose  scales. 
Under  the  microscope  it  appears  very  similar  to  No.  24,  but  shows  no  clue  to  its  original 
mineralogical  constitution. 

No.  23.  This  is  a  green  rock,  which  in  the  hand-specimen  is  almost  massive ;  made 
up  of  an  aggregate  of  fine  lustrous  scales.  Under  the  microscope  the  rock  is  seen  to 
consist  almost  entirely  of  a  matted  aggregate  of  interlacing  scales  with  the  properties 
of  talc.  There  is  also  a  little  calcite  and  magnetite.  This  rock,  then,  is  mainly  a  hydrous 
silicate  of  magnesia,  replacing  some  magnesia-rich  igneous  rock.  The  precise  nature 
of  this  rock  cannot  be  told,  for  all  traces  of  the  original  constituents  have  disappeared. 

No.  24.  This  is  a  green  talcose  rock,  showing  dark  gray  and  light  green  patches;  the 
latter  were  probably  once  feldspar  and  the  rock  originally  a  gabbro.  Under  the  micro- 
scope it  appears  to  be  made  up  of  an  interlacing  matte  of  talcose  scales. 

No.  25.  This  is  a  coarse  rock,  and  to  the  unaided  eye  appears  to  be  made  up  of  feld- 
spar and  chloritic  hornblende.  Under  the  microscope  it  appears  to  be  made  of  cloudy 
feldspar,  magnetite,  and  augite,  partly  altered  to  green  hornblende.  Might  properly  be 
termed  a  diorite,  although  it  was  once  a  gabbro  when  in  a  fresh  condition. 

No.  26.  This  is  a  feldspar  porphyry,  with  bronze-colored  crystals  of  mica.  Under 
the  microscope  the  feldspar  is  seen  to  be  plagioclase.  The  rock  may  have  contained 
augite  once.    Strictly,  it  might  be  termed  a  diorite  porphyrite. 

No.  27.  This  rock  is  very  similar  to  No.  28.  It  contains  more  augite,  and  is  quite 
fresh. 

No.  28.  This  is  a  grayish  rock,  with  rather  indistinct  porphyritic  crystals  of  feldspar. 
Under  the  microscope  it  shows  porphyritic  crystals  of  augite  and  feldspar  in  a  fine 
granular  ground-mass.  This  rock  is  very  different  from  the  greenstones.  It  is  lighter 
colored  and  fresher.  It  might  be  termed  an  augite  porphyrite,  although  the  feldspar 
might  make  it  an  augite-diorite  porphyrite. 

No.  29.  This  is  a  hard  gray  rock,  with  rather  indistinct  crystals  of  white  feldspar. 
Under  the  microscope  it  appears  to  be  badly  decomposed,  showing  remnants  of  twined 
feldspar  crystals,  magnetite,  and  a  dark  constituent  entirely  decomposed.  Might  be 
termed  a  diorite  porphyrite. 

No.  30.  This  is  a  feldspar-quartz  porphyry,  showing  large  crystals  of  quartz,  feldspar, 
and  a  bronze-colored  mica  in  a  fine  ground-mass.  Under  the  microscope  the  quartz 
appears  much  corroded,  and  the  feldspars  clouded.  The  ground-mass  is  made  up  of 
a  fine-grained  aggregate  of  quartz  and  feldspar. 

No.  31.  This  rock  contains  hornblende,  quartz,  and  plagioclase  feldspar  crystals  in 
a  granular  ground-mass.  In  structure  of  components  it  lies  between  a  granite  and  a 
porphyry  and  might  be  termed  a  granite  porphyry. 

No.  32.  This  is  a  rather  fine-grained  greenstone  or  diabase  schist.  It  consists  under 
the  microscope  of  augite,  pale  green  feldspar,  probably  labradorite,  and  iron  ores.  The 
constitutents  are  much  altered. 

No.  33.  This  is  a  quartz-feldspar  porphyry.  It  contains  crystals  of  twined  feldspar 
(plagioclase),  corroded  quartz  crystals,  and  a  decomposed  mineral  possibly  once  horn- 
blende.   There  may  be  some  decomposed  mica.    These  constitutents  lie  in  a  fine 

granular  ground-mass. 

H.  W.  FAIRBANKS,  A.B. 


I 


THE    MOTHER    LODE    REGION — THE   SEVERAL    DIVISIONS.  19 

In  every  mine  accessible  along  the  Central  Lode,  from  the  Pocahontas 
near  Drytown  on  the  north,  to  the  Muldoon  south  of  the  Argonaut  near 
Jackson,  where  ore-bodies  are  found  in  contact  with  or  in  slaty  rocks, 
these  slates  are  observed  to  be  of  the  character  described,  and  which  the 
microscopic  study  of  Mr.  Fairbanks  proves  to  be  the  result  of  alteration 
of  tuffs,  and  not  of  massive  diabase,  as  had  been  supposed  by  the  writer. 

The  normal  tuff  is,  however,  massive,  often  fine-grained  and  containing 
crystals  of  augite,  and  difficult  to  distinguish  from  crystalline  green- 
stone with  the  unaided  eye;  in  this  respect  resembling  the  tufts  of 
Michigan,  described  by  Mr.  Williams,  and  those  described  by  Captain 
Button  as  occurring  in  the  Great  Basin  region  of  Utah. 

The  clay  slates  of  the  Mariposa  beds  are  found  in  cross-cuts  extending 
to  the  eastward  and  westward  of  the  main  fissures  in  these  Amador 
mines.  Usually  the  clay  slates  may  be  readily  distinguished  from  the 
altered  tufts,  but  often  the  slaty  tuffs  graduate  by  insensible  degrees 
into  the  clay  slates,  so  that  no  line  of  demarkation  is  discernible. 

It  is  rarely  that  the  ore  deposits  are  found  in  contact  with  the  fine- 
grained clay  slates,  even  for  a  short  distance.  In  fact,  the  fissures, 
where  passing  through  the  clay  slates  are  usually  destitute  of  value  in 
Amador  County.  This  peculiar  condition,  however,  appears  to  be  local, 
as  in  Calaveras  County  the  richest  portion  of  the  Gwin  Mine  is  in  a 
fissure  cutting  the  black  clay  slates  of  the  Mariposa  beds,  and  in  Mari- 
posa County  the  Princeton  Mine  is  wholly  in  the  clay  slates  of  the 
Mariposa  beds. 

In  Amador  County,  however,  it  seems  important  to  make  the  dis- 
tinction, in  view  of  the  results  obtained  from  veins  in  the  clearly  recog- 
nized clay  slates  and  the  pitted  slates  (altered  tuft's).  Although  the 
mines  of  the  old  Plymouth  Consolidated  Company  at  Plymouth  have 
not  been  accessible  for  many  years,  the  dumps  show  a  large  amount  of 
the  tufaceous  slate,  and  there  is  little  doubt  these  slates  accompanied 
the  ore-bodies.  Four  miles  to  the  northward,  however,  the  Kretcher 
vein  of  the  Bay  State  Company  and  the  veins  of  the  Rhetta  Company 
adjoining  it  on  the  south,  occur  in  the  typical  clay  slates  of  the  Mariposa 
beds,  and  in  these  mines  are  good-sized  veins  of  banded  quartz  carrying 
payable  values. 

The  Dolomitic  Vein. — An  important  geological  feature  of  the  Cen- 
tral Gold  Belt,  and  one  which  repeatedly  appears  from  Mariposa  to 
El  Dorado  County,  is  a  great,  dike-like  vein  of  dolomitic  mineral. 
This  consists  of  carbonate  of  lime  and  carbonate  of  magnesia — a  true 
dolomite — and  in  many  places  there  is  also  found,  in  addition  to  the 
above  minerals,  carbonate  of  iron,  forming  ankerite. 

This  material  occurs  in  great  vein  or  dike-like  masses,  and  is  a  prom- 
inent feature  of  the  lode  in  Mariposa  and  Tuolumne  Counties  and  the 
southern  part  of  Calaveras  County.     It  also  appears  near  San  Andreas, 


20  CALIFORNIA    STATE    MINING    BUREAU. 

and  again  near  Jackson  in  Amador  County,  reappearing  near  Placerville 
in  El  Dorado  County.  Mariposite  is  nearly  always  present,  often  in 
large  amount.  Its  beautiful  green  color  led  early  prospectors  to  believe 
it  was  copper  carbonate.  The  mariposite  is  not  colored  by  copper,  but 
by  chromium. 

The  peculiar  characteristics  of  the  great  dolomitic  vein  are  no  better 
shown  anywhere  along  its  length,  perhaps,  than  at  Coulterville  and 
vicinity.  Just  below  the  village  on  Maxwell  Creek,  the  great  vein 
crosses  that  stream,  which  has  cut  a  gap  through  it  about  100  feet  wide. 
On  the  south  side  of  the  creek  is  located  the  Louisa  Mine,  and  imme- 
diately north  of  it  is  the  Margaret,  on  the  opposite  side  of  the  creek. 
Where  the  lode  crosses  the  creek  it  has  a  width  of  300  feet,  and  consists 
of  an  immense  mass  of  ankerite,  through  which  is  disseminated  the 
green,  scaly  mineral,  mariposite.  Large  lens-shaped  masses  of  quartz 
outcrop  boldly  from  the  ankerite,  being  somewhat  harder  than  the 
latter.  The  lenses  are  irregularly  distributed,  but  occur  mostly  along 
the  hanging-wall  and  near  the  center  of  the  vein.  The  large  veins  or 
lenses  of  quartz  are  separated  by  equally  large  or  larger  zones  of  the 
dolomitic  mineral,  which  is  interlaced  in  every  direction  by  quartz 
veinlets  and  veins  of  varying  size,  making  the  entire  mass  a  mineral 
zone  or  lode  proper.  One  of  the  quartz  lenses  is  nearly  20  feet  in 
width,  outcrops  to  a  height  of  25  feet,  and  is  300  feet  long.  A  shaft 
sunk  on  the  foot-wall  side  of  it  to  a  depth  of  60  feet  showed  it  to  be 
thinning  out ;  but  there  is  no  doubt  that  it  would  be  found  replaced  in 
depth  by  another  lens  of  a  similar  character. 

South  of  this  large  cropping  a  small  vein  branches  out  into  the  hang- 
ing-wall diabase,  striking  northward  and  increasing  in  width  until  it 
disappears  underneath  Maxwell  Creek.  On  the  opposite  side  of  the 
stream  a  large  vein  appears,  which  is  apparently  the  northward  con- 
tinuation of  the  one  referred  to. 

Through  the  center  of  the  lode  is  a  quartz  vein  10  to  20  feet  in  width, 
and  still  west  of  it  is  another,  but  smaller  vein.  The  entire  western 
portion  of  the  ankerite  mass,  constituting  about  one  third  of  the  whole 
width  of  the  zone,  is  a  perfect  network  of  small  quartz  veins,  stringers, 
and  small  bunches  of  quartz. 

A  prominent  feature  of  interest  is  the  union  of  two  of  the  largest 
quartz  lenses  near  the  center  of  the  lode  by  a  third  large  vein,  which 
crosses  the  intervening  ankerite  diagonally.  The  two  large  veins  are 
about  120  feet  apart.  Beginning  near  Maxwell  Creek,  on  one  of  the  large 
outcrops  referred  to,  a  careful  examination  discovers  a  seam  in  the 
quartz,  along  which  gold  may  be  seen  almost  every  foot  of  the  way. 
This  gold  seam  can  be  followed  some  distance  in  a  southerly  direction 
to  where  the  diagonal  branch  above  referred  to  leaves  it.  This  latter 
also  shows  gold  along  a  similar  seam,  leading  to  the  other  large  quartz 


THE   MOTHER    LODE    REGION — THE    SEVERAL    DIVISIONS.  21 

lens  parallel  to  the  first,  and  here,  again,  is  a  gold  seam  which  may  be 
followed  if  care  be  taken.  Outside  of  the  gold  thus  occurring,  none  was 
observed  elsewhere  by  the  writer,  though  it  was  said  that  prospects  could 
be  obtained  by  crushing  certain  portions  of  the  rock  and  carefully  pan- 
ning it. 

Southward  from  the  section  above  described,  the  several  large  veins 
converge  toward  a  central  point  on  the  ridge,  which  rises  higher  and 
higher,  terminating  in  an  immense  mass  of  quartz  at  its  apex.  South- 
ward from  this  point  the  quartz  is  less  prominent  and  the  ankerite  con- 
stitutes the  major  portion  of  the  lode  until  another  occurrence  of  quartz 
lenses  is  reached,  which  in  each  case,  whether  following  the  lode  north 
or  south,  is  much  the  same. 

Gold  sometimes  occurs  in  the  ankerite  and  mariposite,  when  seamed 
with  quartz.  A  brecciated,  crushed  condition  of  this  rock  seems  to  favor 
the  gold,  or,  at  least,  rock  of  this  character  contains  more  gold  than  that 
which  is  massive  and  solid.  The  entire  mass  is  low-grade,  and  ankerite 
wholly  free  from  quartz  is  practically  free  from  gold  in  this  mine. 

The  characteristics  as  above  described  are  peculiar  to  the  occurrence 
of  the  dolomitic  vein  wherever  it  appears.  Often  large  masses  of  it 
are  found  crushed,  sheared,  and  altered  to  talc  schist  or  to  a  granular 
talcose  mass,  including  many  angular  fragments  of  crystalline  mineral. 
In  the  Rawhide  Mine  in  Tuolumne  County  was  found  a  notable  excep- 
tion to  the  usually  observed  condition.  At  one  place  in  this  mine  the 
ankerite  and  mariposite  were  found  phenomenally  rich  in  gold. 

As  a  matter  of  course,  the  description  of  the  occurrence  at  Coulterville 
is  not  absolutely  duplicated  anywhere  along  the  lode,  but  it  is  typical 
in  its  general  features  of  the  dolomitic  vein  throughout  the  length  of 
the  lode.  In  the  Pacific  Mine  at  Placerville,  the  talc  schist  resulting 
from  the  alteration  of  the  dolomite  contains  1  to  2  per  cent  of  iron 
sulphide,  but  whether  or  not  it  is  auriferous  was, not  ascertained. 

The  mines  of  the  Central  Gold  Belt,  where  not  in  the  dolomitic  vein, 
occur  in  black  clay  slates,  in  tufaceous  black  slates,  and  in  amphibolite 
schist,  and  are  described  under  their  proper  heading. 

The  East  Lode. — The  mines  of  the  East  Lode,  which  are  found  from 
6  to  18  miles  east  of  the  Central  Belt,  occur  in  the  slates  of  the  Calaveras 
formation  and  in  grano-diorite.  Some  of  the  most  important  of  these 
mines  are  found  in  the  latter  formation,  and  a  description  of  their 
general  characteristics  is  of  interest. 

Granite  areas  in  which  gold-bearing  veins  occur  are  found  in  Mariposa 
County,  near  Kite's  Cove;  in  Tuolumne  County,  near  Groveland,  near 
Columbia,  and  at  Summersville  and  vicinity;  in  Calaveras  County,  at 
West  Point  and  vicinity;  in  Amador,  at  Pioneer;  in  El  Dorado,  at 
several  localities;  and  in  Nevada  County,  at  and  near  Grass  Valley  and 
Nevada  City. 


22  CALIFORNIA   STATE   MINING   BUREAU. 

Veins  in  Granite. — In  the  several  granite  areas  referred  to  occur  a 
large  number  of  veins,  some  of  which  appear  entirely  independent  of  all 
others,  and  in  other  instances  are  found  systems  of  connected  fissures, 
which  were  evidently  produced  by  a  common  cause.  These  veins  have 
definite  characteristics,  and  the  ores  are  noticeably  similar  throughout 
the  entire  granitic  region  referred  to.  They  are  usually  easily  dis- 
tinguishable by  their  physical  appearance  from  the  ores  occurring  in 
other  formations,  whether  in  the  same  vicinity  or  from  some  distant 
point. 

The  strike  and  dip  of  these  veins  in  granite  are  not  at  all  uniform, 
in  this  respect  differing  greatly  from  the  veins  of  the  Central  Belt, 
which  almost  universally  strike  west  of  north  and  dip  easterly.  In  the 
granite  areas  the  veins  have  no  uniform  strike,  but  are  found  from  true 
east  and  west  courses  around  to  north,  and  at  all  angles  between  them. 
The  dip  is  no  more  uniform  than  the  strike.  Whatever  the  direction  of 
dip  of  a  vein,  it  is  usually  not  persistent  at  or  near  any  particular 
angle,  but  varies  from  a  low  angle  to  nearly  or  quite  perpendicular. 
Not  infrequently,  in  depth  a  vein  will  dip  in  an  opposite  direction  from 
that  which  it  has  at  and  near  the  surface.  The  veins  occur  along  lines 
of  fissuring.  These  fissures  are  found  singly,  in  pairs,  and  in  many 
places  as  zones  of  fracture  of  varying  width,  comprising  several  fissures 
having  an  ai3proximate  parallelism.  These  fissures,  singly  and  in 
groups,  are  often  planes  of  movement,  as  evidenced  by  slickensides  and 
gouge  seams.  In  many  cases  these  zones  of  fracture  are  found  to 
consist  of  crushed  granitic  material,  greatly  altered,  and  in  some 
instances  containing  vein  quartz  in  a  granulated  condition,  indicating 
that  a  movement  of  the  rock-masses  has  taken  place  subsequent  to  the 
deposition  of  the  quartz.  In  certain  more  rare  cases,  this  brecciated  or 
granulated  quartz  has  been  cemented  by  a  still  more  recent  infiltration 
of  silica.  In  these  crushed  zones  the  feldspars  are  thoroughly  kaolinized; 
the  bi-silicates  are  altered  to  chloritic  mineral,  and  the  whole  mass  is 
soft  and,  when  wet,  sometimes  mushy,  forming  dangerous  ground  to 
mine.     Often  it  is  gold-bearing,  though  seldom  rich. 

In  the  same  fissure  plane  or  zone  are  found  the  concentrated  mineral 
deposits  forming  the  ore-bodies  proper  of  the  mines.  In  some  places 
they  lie  at  the  side  of  these  crushed,  partially  silicified  zones,  either  in 
direct  contact  with  them  or  separated  by  a  strip  or  wedge  of  hard 
granite,  but  little  altered.  In  other  instances  they  are  found  as  sepa- 
rate ore-shoots,  connected  with  the  previously  described  crushed  zones 
only  by  a  clay  seam.  Other  masses  of  quartz  occur  in  these  fissures, 
which  contain  very  little  of  either  gold  or  sulphide  mineral. 

These  veins  are  undoubtedly  the  result  of  substitution  of  silica,  cal- 
cite,  and  other  minerals  for  the  original  soluble  constituents  of  the 
granite,  having  been  conveyed  to  the  point  of  deposition  by  mineral 


THE    MOTHER   LODE    REGION — THE    SEVERAL    DIVISIONS.  23 

solutions,  probably  derived  from  a  deep-seated  source.  The  most  com- 
plete replacement  has  evidently  occurred  where  the  Assuring  and  crush- 
ing have  been  greatest.  The  vein  quartz  is  found  exhibiting  every  phase 
of  condition  from  a  partial  alteration  of  the  granitic  mass,  almost  a 
normal  granite  (though  the  feldspars  are  always  carious,  and  a  small 
percentage  of  finely  divided  iron  sulphide  may  usually  be  observed), 
through  the  various  stages  of  transition,  finally  reaching  the  most  com- 
plete alteration  to  crystalline  quartz,  sometimes  heavily  impregnated 
with  the  sulphides  of  iron,  lead,  copper,  zinc,  and  silver,  with  gold  and 
other  minerals  more  rare.  Calcite  is  a  frequent  accompaniment,  both 
in  the  quartz  and  in  the  crushed  zones  of  granite.  The  vein  quartz 
occurs  in  a  variety  of  conditions — as  a  vitreous,  colorless,  granular  rock  ] 
a  milk-white,  semi-greasy  kind ;  a  bluish-black  variety,  usually  vitreous ; 
also  in  alternating  bands  of  bluish  and  white  rock,  and  as  granulated 
quartz.  All  of  these  varieties  are  gold-bearing,  and  again  all  kinds  are 
barren.  All  are  associated  with  sulphide  minerals,  and  all  again  occur 
with  scarcely  a  trace  of  them.  The  banded  varieties  are  usually  of  fair 
grade  in  gold,  and  the  appearance  of  galena  is  often  an  index  of  value. 
Some  of  the  zinc  ores  are  also  high-grade.  The  sulphide  minerals  con- 
tain from  $50  to  $1000  per  ton  in  gold,  and  some  are  also  correspond- 
ingly rich  in  silver,  though  the  silver  contents  are  usually  relatively 
small.  The  sulphides  are  pyrite,  marcasite,  mispikel,  chalcopyrite, 
galena,  blende,  and  pyrrhotite.  The  latter  is  peculiarly  characteristic 
of  granite  formations  throughout  California,  particularly  in  the  ore- 
bodies  of  larger  size.  Tellurides  of  gold  occur  sparingly  in  several 
localities.  The  ore-shoots  vary  greatly  in  width  and  length,  though  the 
veins  sometimes  have  a  width  of  30  feet  or  more,  as  in  the  Black  Oak 
Mine  in  Tuolumne  County.  Ordinarily,  however,  the  shoots  are  less 
than  100  feet  in  length  and  average  between  6  inches  and  2  feet  in 
width.  Often  the  lenses  have  an  average  length  of  20  feet,  but  succeed 
each  other  immediately,  the  ends  often  overlapping,  thus  forming  prac- 
tically a  continuous  shoot  of  considerable  length. 

Occasionally  are  found  two  veins  approximately  parallel  and  sepa- 
rated by  1  to  4  feet  of  granite  in  a  more  or  less  advanced  condition  of 
alteration,  as  is  the  case  in  the  Good  Hope  Mine,  near  Ferris  in  River- 
side County.  The  branching  tendency  of  the  fissures  is  a  pronounced 
characteristic.  Usually  one  wall  at  least  is  well  defined — generally  the 
foot — the  zone  of  fracture  and  crushing  extending  to  various  distances 
into  the  hanging-wall.  Now  and  then  a  perfectly  defined  hanging-wall 
will  be  found,  but  progressing  along  this  wall  it  is  seen  to  diverge  gradu- 
ally from  the  plane  of  the  foot  and  its  influence  as  a  bounding  plane  is 
lost,  another  slip  or  wall  taking  its  place.  This  continues  indefinitely 
until  the  identity  of  the  entire  vein  is  lost  in  the  numerous  branching 
cracks  which  extend  into  the  granite.     Often  a  well-defined  vein  several 


24  CALIFORNIA    STATE   MINING   BUREAU. 

feet  in  width  will  thus  pinch  out  to  the  merest  crack,  in  which  is  found 
no  sign  of  clay  or  of  movement,  and  it  requires  the  most  careful  obser- 
vation to  follow  it  at  all ;  but  usually  by  persisting  in  the  general  direc- 
tion of  the  course  of  the  vein  it  may  be  found  to  reopen  and  new  shoots 
of  ore  found.  Sometimes,  however,  after  drifting  fruitlessly  some  dis- 
tance, a  cross-cut  is  advisable.  In  some  instances  these  pinches  are 
several  hundred  feet  long  and  the  ground  very  hard. 

The  formation  of  many  short  shoots  of  rich  ore  in  portions  of  the 
fissure  where  the  walls  are  several  feet  apart  is  an  interesting  feature. 
It  is  not  uncommon  to  find  a  wedge  of  quartz  forming  on  the  foot-wall, 
which  gradually  widens  to  1  or  2  feet  when  it  leaves  the  foot-wall,  crosses 
the  fissured  zone  at  a  low  angle,  and  joins  the  hanging-wall,  where  it 
thins  out  and  is  lost.  Between  the  short  shoot  of  ore  thus  formed  and 
its  parting  from  the  foot-wall  there  may  be  found  several  stringers  of 
quartz  parallel  with  the  foot,  or  the  entire  space  may  consist  of  a  reticu- 
lated group  of  small  veins  and  seams,  while  along  the  foot-wall  a  second 
wedge-shaped  vein  of  quartz  Avill  appear,  which  will  repeat  the  peculiari- 
ties of  the  shoot  adjoining  as  described.  The  granite  adjacent  to  the 
vein,  and  occurring  as  horses  within  it,  is  frequently  gold-bearing  to  a 
considerable  extent,  sometimes  in  sufficient  quantity  to  be  visible  to  the 
naked  eye. 

It  is  the  custom  to  sort  out  the  granite  as  waste,  but  it  should  be  done 
with  caution,  for  it  not  infrequently  pays  to  send  the  entire  contents  of 
the  vein  to  mill,  when  in  the  pay  shoot.  The  fact  that  several  old  dumps 
have  been  worked  at  a  profit  is  evidence  that  early  methods  were  careless 
in  this  regard.  In  some  respects  these  mines  are  worked  at  a  disad- 
vantage, for  it  is  easy  to  lose  the  vein  where  a  pinch  occurs,  and  it  has 
led  in  numerous  cases  to  the  closing  of  what  are  probably  good  mines. 
What  has  been  described  as  occurring  along  the  vein  horizontally  is 
equally  applicable  to  the  fissure  in  depth,  and  a  pinch  in  the  shaft  does 
not  signify  that  the  limit  of  the  vein  has  been  reached  any  more  than  it 
does  when  occurring  in  the  face  of  a  drift. 

These  disadvantages  are  greatly  oflset,  however,  by  the  high  grade  of 
ore,  which  is  uniformly  much  higher  grade  than  that  in  larger  veins  in 
other  formations.  Often  the  ores  from  the  veins  in  granite  may  be 
shipped  to  distant  smelters  with  profit  after  rough  sorting. 

Dikes  are  of  frequent  occurrence  throughout  the  granite  area  in  the 
neighborhood  of  the  mineral  belt.  They  are  of  various  types,  but  the 
most  common  are  granitic  dikes  of  coarse  crystallization  and  dark  green 
diorites  of  fine  grain,  extremely  tough  and  hard.  The  former  are  char- 
acterized by  the  occurrence  of  masses  and  crystals  of  albite,  tourmaline, 
and  biotite.  The  peculiar,  interwoven,  grate-like  structure  of  quartz 
and  feldspar,  known  as  graphic  granite,  is  of  frequent  occurrence  in 
these  dikes.     These  granitic  intrusions  are  usually  older  than  the  veins, 


THE   MOTHER    LODE    REGION — THE    SEVERAL   DIVISIONS.  25 

though  there  are  exceptions.  The  diorite  dikes,  however,  are  generally- 
younger  and  cut  the  veins.  The  dikes,  as  a  rule,  cross  the  line  of  strike 
of  the  veins,  though  not  always.  Whether  or  not  these  dikes  have  any 
important  influence  on  ore  deposition  is  a  question. 

In  some  instances  ore-shoots  are  found  lying  with  the  granitic  dikes, 
the  downward  pitch  of  the  ore-body  being  coincident  with  the  dip  of  the 
dike.  The  influx  of  large  quantities  of  water  is  a  usual  accompaniment 
of  the  development  of  these  veins.  It  often  comes  with  a  rush  at  unex- 
pected times.  A  mine  may  be  developed  to  considerable  depth  and 
have  encountered  but  little  water,  when  without  warning  a  blast  will 
break  into  what  is  called  by  the  miners  a  reservoir  or  pocket,  though 
usually,  in  fact,  a  system  of  fissures  filled  with  water  derived  from  the 
surface.  The  deeper  the  point  in  the  mine  at  which  these  water  crevices 
are  struck,  the  greater  the  force  of  the  water.  Often  the  lower  levels 
are  completely  flooded,  and  weeks  are  required  to  pump  out  the  water, 
but  in  time  the  reservoir  is  exhausted,  and  things  resume  their  usual 
condition.  Another  water-rush  may  not  occur  in  many  months,  and 
again  in  some  places  they  have  been  found  in  quick  succession.  In  one 
instance  a  water  crevice  was  broken  into  in  the  Black  Oak  Mine  in 
Tuolumne  County  at  a  depth  of  600  feet.  With  considerable  difficulty 
a  bulkhead  was  constructed,  and  the  pressure  gauge  indicated  at  one 
time  a  standing  pressure  of  180  pounds  to  the  square  inch,  indicating 
that  the  height  of  this  reservoir  was  not  less  than  400  feet.  The  flow 
being  controlled  by  means  of  a  valve,  the  pumps  in  time  removed  the 
water  and  a  normal  condition  was  again  reached.  After  several  months 
the  bulkhead  was  torn  out  and  a  round  of  holes  was  drilled  in  the  face 
and  discharged,  upon  which  the  water  again  rushed  into  the  mine  work- 
ings in  as  great  volume  as  before.  The  probability  is  that  in  some 
manner  the  vent  to  the  reservoir  had  become  clogged  and  the  flow  of 
water  stopped.  The  force  of  the  blast  removed  the  obstruction,  and  the 
water  again  poured  into  the  mine  workings,  but  it  finally  was  drained  to 
a  considerable  extent.  This  shows  the  necessity  for  abundant  capacity 
to  handle  water.  Some  claim  that  large  flows  of  water  are  an  indica- 
tion of  valuable  ore  deposits,  but  there  is  really  no  apparent  relation 
between  ore  deposits  and  large  flows  of  water.  The  ore  was  deposited 
by  ascending  currents,  and  the  water  found  in  mines  is  always  found 
coming  down  from  the  direction  of  the  surface.  Sometimes  water  may 
be  seen  bubbling  up  from  the  lowest  levels  of  the  mine  as  though  from 
an  ascending  current,  but  a  case  of  this  kind  is  due  to  hydrostatic 
pressure,  the  water  flowing  in  coming  from  some  point  higher,  through 
a  series  of  connected  cracks  or  fissures. 

A  peculiarity  of  these  veins  in  granite  near  the  surface  may  often  be 
observed  in  the  occurrence  of  open  cracks  traversing  the  vein  in  a  hori- 
zontal direction,  reaching  from  wall  to  wall,  and  dividing  the  vein  into 


26  CALIFORNIA    STATE   MINING    BUREAU. 

blocks  by  a  series  of  floors,  as  it  were,  at  quite  regular  intervals  of  a  foot 
or  thereabouts,  depending  somewhat  on  the  width  of  the  vein.  The 
blocks  are  separated  by  1  to  4  inches  of  space,  in  which  have  accumu- 
lated clay  and  grit,  quartz  crystals,  iron  oxide,  and  other  secondary 
products  and  gold.  The  amount  of  gold  is  largely  in  excess  of  the 
amount  found  in  an  equal  weight  of  quartz  of  the  vein  itself  in  many 
cases.  This  peculiar  occurrence  is  undoubtedly  due  to  a  sort  of  molecu- 
lar expansion  of  the  granitic  mass,  chiefly  due  to  the  alteration  of  the 
feldspars,  and  in  a  less  degree  possibly  to  the  change  which  has  taken 
place  in  the  other  constituents  of  the  granite  caused  by  surface  decay 
and  meteoric  agencies  generally.  It  is  an  interesting  fact,  and  afl:brds 
food  for  study  and  investigation. 

The  occurrence  of  gold  in  the  silt-like  material  lying  on  these  floors 
may  be  due  partly  to  the  quartz  itself,  but  more  probably  comes  from 
the  oxidized  sulphides,  and  also  in  part  perhaps  by  infiltration  from 
the  selvages  of  the  vein,  if  not  from  the  granite  itself,  which  may  have 
become  gold-bearing  by  impregnation  from  the  fissure.  Attrition,  due 
to  movement,  may  also  have  been  partly  responsible  for  the  occurrence 
of  this  gold.  When  the  oxidized  zone  is  passed  and  the  granite  becomes 
normal,  these  floors  no  longer  appear. 

In  many  places  the  quartz  is  perfectly  free  from  both  walls,  and  again 
but  one  wall  is  free,  the  opposite  side  being  frozen.  In  an  equal  num- 
ber of  cases  the  vein  is  frozen  on  both  walls.  These  variations  are  not 
constant,  for  a  vein  may  be  free  at  one  place  and  frozen  in  another. 
These  changing  conditions  may  be  considered  as  indicating  something 
of  the  relation  of  the  original  fissure  to  the  ore  deposit.  Where  both 
walls  are  free,  it  is  not  unlikely  that  the  ore  is  filling  the  space  bounded 
between  two  fissures.  Where  one  wall  is  free  the  mineralization  has 
progressed  along  one  side  of  the  fissure  plane  only;  and  where  both 
walls  are  frozen,  it  would  seem  to  indicate  that  ore  deposition  progressed 
outwardly  from  a  single  crack,  or  possibly,  in  the  case  of  a  large  ore.- 
body,  the  mineralization  has  impregnated  the  walls  beyond  the  limiting 
planes  of  the  fissured  zone,  to  an  extent  suflficient  to  constitute  ore,  and 
has  stopped  only  when  the  mineral  solutions  were  unable  to  penetrate 
farther  from  the  fissure  plane  itself. 


METHODS  OF  MINING. 

The  mining  methods  in  vogue  on  the  Central  Lode  of  California  are 
not,  in  the  opinion  of  the  writer,  those  calculated  to  produce  the  best 
results,  when  viewed  from  the  standpoint  of  economy.  They  are,  with 
few  exceptions,  the  methods  of  thirty,  of  forty,  and  of  fifty  years  ago,  and 
some  of  the  practices  are  so  primitive  in  their  nature  as  to  savor  of 
past  centuries  rather  than  of  decades. 


THE    MOTHER    LODE    REGION — METHODS    OF    MINING.  27 

A  policy  which  obtains  throughout  the  mining  districts  of  California 
is  that  of  demanding  prompt  returns  from  ore  development,  which  is  of 
course  very  desirable,  but  which  in  many  cases  works  ultimately  to  the 
disadvantage  of  the  owner,  and  the  manager  or  superintendent  is  so 
completely  handicapped  that  he  is  unable  to  make  substantial  head- 
way. There  are  certain  districts  where  this  demand  for  "immediate 
returns"  does  not  act  so  disadvantageously,  but  in  the  mines  of  the 
Central  Lode  it  is  undoubtedly  a  short-sighted  policy.  The  reason  for 
this  will  become  apparent  when  it  is  understood  that  with  few  excep- 
tions the  ground  is  heavy — often  swelling  and  crushing  the  heaviest 
timbers.  The  usual  practice  is  to  drive  a  cross-cut  or  drift  from  a 
station  at  the  shaft  to  the  vein.  This  may  or  may  not  at  once 
encounter  ore;  if  not,  a  drift  is  driven  along  the  fissure,  which  must  be 
timbered  in  the  most  substantial  manner.  These  drifts  are  usually 
not  less  than  7  feet  high,  4  to  5  feet  wide  at  the  top,  and  7  to  8  feet  at 
the  bottom.  These  dimensions  are  all  inside  the  timbers.  It  usually 
makes  little  difference  whether  the  cutting  is  in  ore  or  not,  the  ground 
is  generally  heavy.  The  fissures  are  often  from  10  to  40  feet  wide,  and 
the  miners  (of  Amador  County  particularly)  are  well  acquainted  with 
the  danger,  diflficulty,  and  expense  attending  this  kind  of  mining.  As 
soon  as  pay  rock  is  encountered  it  is  hoisted  and  sent  to  the  mill,  and 
the  drift  continues,  while  overhand  stopes  are  started  and  development 
proceeds.  It  may  be  several  hundred  feet  to  the  limit  of  the  property, 
and  is  often  over  1000  feet,  and  this  heavy  swelling — sometimes  run- 
ning— ground  must  be  kept  open  until  the  entire  level  has  been  explored 
and  the  ore  to  the  level  above  all  extracted  and  sent  to  the  surface.  An 
idea  of  the  character  of  some  of  this  ground  may  be  gained  from  the 
statement  that  in  a  certain  instance  a  drift  of  usual  size  being  driven 
a  distance  of  200  feet,  at  the  rate  of  5  feet  or  more  daily,  under  con- 
tract, could  not  be  completed  before  it  became  necessary  to  return  to 
that  portion  first  driven  for  the  purpose  of  retimbering.  The  timbers 
employed  in  holding  ground  of  this  character  are  usually  20  to  30 
inches  in  diameter,  and  it  is  no  uncommon  thing  to  see  these  immense 
logs,  a  few  weeks  after  being  put  in  place,  split,  crushed,  and  broken  as 
though  they  were  incapable  of  offering  any  resistance  to  this  all  but 
irresistible  force. 

The  advisability  of  cutting  the  main  gangways  in  the  hard  rock  of 
the  walls,  either  foot  or  hanging,  and  reaching  the  vein  by  a  system  of 
cross-cuts,  is  advised.  This  has  not,  as  yet,  at  this  writing,  been 
attempted,  but  its  feasibility  and  desirability  can  readily  be  appreciated 
when  the  character  of  the  main  fissure,  as  above  explained,  is  understood. 

These  main  gangways,  being  driven  in,  say  the  foot-wall,  should  have 
cross-cuts  extending  at  right  angles  to  the  direction  of  the  main  gang- 
way.    These  should  be  disposed  at  stated  intervals  for  the  purpose  of 


28  CALIFORNIA    STATE    MINING    BUREAU. 

prospecting  the  fissure  and  to  render  accessible  the  ore  discovered.  In 
slate,  the  main  gangways  should  be  at  a  distance  of  40  to  60  feet  from 
the  vein — where  in  greenstone,  they  may  be  driven  nearer  the  vein.  The 
cross-cuts  should  be  driven  at  stated  intervals,  a  greater  or  less  distance 
apart  according  to  the  character  of  the  ground  adjacent  to  the  vein- 
When  the  ground  is  very  bad,  the  cross-cuts  should  be  closer,  and  when 
less  so,  at  longer  intervals.  In  most  cases,  if  driven  at  intervals  of  240 
feet,  the  distance  will  be  found  convenient.  Raises  should  always  be 
put  through,  connecting  with  the  level  above,  before  stoping  is  com- 
menced. Very  often  this  important  matter  is  neglected,  owing,  as  pre- 
viously stated,  to  a  desire  to  realize  a  profit  on  the  ore  as  quickly  as 
possible.  These  raises  should  be  put  in  about  60  feet  apart;  this, 
beginning  30  feet  from  the  point  where  the  cross-cut  reaches  the  vein, 
will  admit  of  four  raises  within  the  240-foot  section  suggested,  the  vein 
being  worked  30  feet  each  side  of  the  raise. 

When  putting  through  raises,  it  is  really  an  economical  plan  to  sink 
a  winze  from  the  level  above  to  meet  the  raise.  By  this  means  ventila- 
tion will  be  more  quickly  obtained,  and  the  additional  work  which  men 
can  accomplish  will  soon  pay  for  the  increased  cost  of  sinking  the 
winze.  Men  will  not  and  cannot  perform  the  best  work  most  expe- 
ditiously in  a  foul  atmosphere,  though  this  fact  seems  to  be  lost  sight 
of  by  many  mine-owners. 

In  addition  to  the  great  disadvantage  of  foul  air,  when  the  raises  are 
not  put  through,  the  heavy  timbers  must  be  hoisted  through  the  raise 
into  the  stopes  by  means  of  block  and  tackle  at  great  expense  of  time. 
If  the. raise  were  through,  the  cost  of  handling  these  great  timbers  would 
be  very  materially  reduced  by  lowering  them  through  the  raise  from 
the  level  above  to  the  floor  of  the  stope  where  they  are  to  be  placed  in 
position. 

With  the  lateral  drifts  and  cross-cuts  completed,  and  drifts  driven  on 
the  vein,  with  raises  through  to  the  next  level  above,  the  work  of  stoping 
can  be  carried  on  at  as  many  points  as  may  be  desired,  and  in  a  few 
weeks,  or  months  at  most,  the  greater  portion  of  the  excavation  made  on 
the  vein,  where  not  filled,  will  collapse  and  be  closed  up  forever.  This 
works  no  harm  or  inconvenience,  as  the  main  lateral  drift  remains  open. 

When  operating  in  this  manner,  filling  for  the  stopes  may  be  taken 
from  the  hanging-wall  by  driving  an  inclined  raise  into  it  and  opening 
out  a  chamber.  The  rock  broken  in  these  chambers  will  pass  by  gravity 
down  into  the  stopes  beneath  and  fill  them,  little  or  no  shoveling  being 
necessary.  This  method  of  mining  and  filling,  when  properly  carried 
out,  will  prove  more  safe  and  far  less  expensive  than  some  of  the  methods 
heretofore  employed  in  California  mines.  In  some  mines,  if  stoping  be 
expeditiously  prosecuted  in  the  manner  above  suggested,  no  filling  will 
be  required,  the  timbers  affording  all  the  support  necessary,  but  in  most 


THE   MOTHER    LODE    REGION METHODS   OP   MINING. 


29 


cases  filling  of  the  stopes  is  advised.  Where  the  hanging-wall  country 
adjacent  to  the  vein  has  a  tendency  to  cave,  it  may  be  that  the  inclined 
upraise  for  the  purpose  of  obtaining  filling  for  the  stopes  may  be  inex- 
pedient. In  that  case,  a  horizontal  cross-cut  may  be  driven  to  the  solid 
ground  of  the  hanging,  that  portion  nearest  the  vein  being  securely 
timbered.  The  filling  must  then  be  distributed  by  means  of  wheel- 
barrows. 


nQetl^od  of  Woi'Klno  v^eiVis  in  61^^1(117°  (ground, 

Fig.  2. 

These  filling  chambers  may  be  worked  with  hand  or  power  drills, 
large  or  small,  as  seems  desirable.  One  of  the  greatest  items  of  mining 
expense,  as  now  practiced,  is  that  of  constantly  relieving  swelling  or 
running  ground,  and  retimbering.  When  the  ore-shoot  is  attacked  in 
sections  by  cross-cuts  from  the  lateral  drift,  any  particular  section  need 
remain  open  only  a  few  months  at  most,  instead  of  two,  three,  or  more 
years,  as  now. 


30  CALIFORNIA   STATE    MINING   BUREAU. 

Another  advantage  may  be  derived  by  driving  an  intermediate  level 
midway  between  the  main  levels,  if  the  ground  is  particularly  bad,  and 
connecting  with  the  cross-cut  or  gangway  beneath  by  a  raise.  In  this 
manner  the  floor  of  the  lower  main  level  need  only  be  maintained  about 
half  the  time  that  would  be  necessary  if  all  ore  were  sent  down  to  the 
main  level  through  a  mill-hole  extending  upward  100  feet  more  or  less, 
and  connecting  two  main  levels.  This  plan  would,  of  necessity,  require 
that  a  raise  be  cut  through  solid  rock  from  the  vicinity  of  the  main 
gangway  to  the  foot- wall  of  the  vein,  reaching  it  about  midway  between 
two  levels.  Each  of  these  raises  would  have  an  approximate  height  of 
45  to  60  feet,  and  would  cost,  perhaps,  when  timbered,  $500;  but  the 
expense  of  keeping  open  the  level  in  the  vein  would  soon  offset  this 
expense  if  the  ground  were  very  bad.  As  a  matter  of  course,  the  super- 
intendent must  determine  when  an  intermediate  level  and  auxiliary 
raise  are  justifiable.  His  experience  with  the  ground  in  the  fissure  will 
dictate  whether  the  plan  suggested  is  advisable  or  not.  The  sketch 
(Fig.  2)  on  page  29  illustrates  the  idea. 

Timbering. — The  timbers  employed  in  the  mines  of  the  Central  Lode 
are  uniformly  large — 18  to  30  inches  in  diameter — and  the  method  of 
framing  and  placing  them  varies  somewhat,  but  is  usually,  in  the  larger 
stopes,  some  modification  of  the  system  known  throughout  the  world  as 
the  Nevada  square-set.  The  placing  of  these  timbers  is  accomplished 
often  under  great  disadvantage,  and,  in  some  instances,  with  consider- 
able evident  danger.  The  men  selected  for  this  work  usually  represent 
the  finest  type  of  physical  manhood,  for  no  others  could  accomplish 
the  arduous  task  expeditiously.  As  to  the  relative  merits  of  the  respec- 
tive methods  of  framing  these  heavy  timbers,  it  seems  only  necessary 
to  say  that  those  systems  involving  the  least  framing  with  ax  and  adz 
underground,  and  consequent  smaller  loss  of  time  in  placing  timbers  in 
position,  are  the  methods  best  adapted  to  regular  practice. 

In  some  mines  an  objection  is  raised  to  the  employment  of  sills  on  the 
main  floor  of  a  level,  for  the  reason  that  the  sills  rot  before  the  stopes  can 
be  carried  through  from  any  level  to  the  next  above.  In  most  cases  there 
is  no  excuse  for  this.  A  reprehensible  practice,  which  is  found  almost 
universal  in  these  mines,  is  that  of  attempting  to  carry  up  stopes  of 
too  large  a  superficial  area,  and  this  practice  is  responsible  for  some 
disastrous  caves  which  have  occurred  in  various  mines.  A  stope  of 
smaller  superficial  area  can  generally  be  carried  from  one  level  to  the 
next  above  more  quickly  and  safely  than  a  large  one,  and  in  most  cases, 
even  by  the  present  "old-fashioned"  methods  of  mining,  a  stope  of 
small  sectional  area  may  be  carried  through  in  a  few  months — long 
before  the  sills  become  weakened  by  reason  of  decay.  If  the  develop- 
ment of  the  mine  were  carried  on  well  in  advance  of  the  extraction  of  the 
ore,  it  would  not  be  found  necessary  to  open  these  large  stopes,  as  a  num- 


J 


THE    MOTHER    LODE    REGION — METHODS    OF    MINING.  31 

ber  of  smaller  stopes  would  supply  the  same  amount  of  ore  daily  as  is 
usually  drawn  from  one,  two,  or  three  large  stopes,  and  it  would  be 
found  that  ultimately  the  cost  would  be  materially  less,  as  in  most  cases 
there  would  be  no  loss  of  ore,  no  disastrous  caves,  and  work  could  be 
accomplished  more  expeditiously  and  more  cheaply. 

Filling. — There  are  few  veins  on  the  Central  Lode  where,  by  present 
mining  methods,  filling  is  not  absolutely  necessary,  though  by  the  adop- 
tion of  the  lateral  foot-wall  gangway  system  heretofore  suggested,  in 
some  of  the  smaller  mines,  filling  might  to  some  extent  be  dispensed 
with,  the  walls  being  allowed  to  collapse  after  removing  the  ore.  Mate- 
rial for  filling  is  usually  obtained  from  cross-cuts  and  drifts  driven  in 
prospecting,  and  from  chambers  cut  in  the  walls  of  the  veins — generally 
the  hanging-wall.  There  are  few  veins  on  the  lode  so  small  as  to  make 
enough  waste  in  stoping  to  fill  the  excavation.  Ordinarily,  all  the 
rock  removed  from  the  pay-shoot  goes  to  the  mill,  and  filling  must  be 
obtained  elsewhere.  In  some  of  the  larger  mines,  where  the  veins  are  of 
great  size — 40  to  100  feet  or  more  in  width — it  is  not  uncommon  to  find 
the  entire  vein  removed  for  a  distance  along  its  strike  equal  to  and  often 
much  greater  than  its  width,  the  entire  area  overhead  resting  upon  the 
props  reaching  from  the  topmost  set  of  timbers  to  the  roof.  There  may 
be  three,  four,  or  more  floors  in  place,  and  the  stope  may  be  found  filled 
from  the  sill  floor  to  within  a  floor  or  two  from  the  top;  but  it  is  clearly 
evident  that  in  a  stope  of  the  size  indicated,  this  filling  can  afford  but 
little  if  any  support  to  the  hanging-wall,  and  none  at  all  to  the  back  of 
the  stope.  Failure  to  recognize  this  fact  has  resulted  disastrously  in 
more  than  one  mine.  The  filling  must  be  placed  in  such  manner  as  to 
support  the  back  of  the  stope  over  as  large  an  area  as  possible,  and  a 
portion  of  this  filling  at  least  must  be  placed  by  hand,  for  it  is  clearly 
evident  that  should  any  subsidence  occur  in  a  stope  approximating  100 
feet  square,  timbers  cannot  be  depended  on  to  support  the  great  weight. 
In  a  stope  having  a  width  and  length  of  100  feet  and  carried  up  four 
floors  in  height,  there  would  remain  between  the  top  set  and  the  floor  of 
the  level  next  above  (65  feet)  not  less  than  50,000  tons  of  ore.  Should 
this  become  ''dead  weight,"  each  post  of  the  sets  in  place  would  have  to 
sustain  a  load  of  several  hundred  tons  of  ore  in  addition  to  the  weight 
coming  from  ore  and  filling  in  levels  above,  and  to  this  must  be  added 
the  greater  pressure  coming  from  the  direction  of  the  hanging-wall. 
This  weight,  or  pressure,  will  vary  greatly  in  different  mines,  depending 
upon  the  character  of  the  ground,  the  condition  of  the  walls,  and  to  no 
small  extent  upon  the  angle  of  dip  of  the  vein.  Were  the  enormous 
weight  of  this  great  shifting  mass  of  rock  equally  distributed,  there 
would  be  less  probability  of  a  cave;  but  often,  the  weight  being  trans- 
ferred from  point  to  point,  owing  to  the  mobility  of  the  ground,  the 
pressure  upon  some  given  point  becomes  greater  than  the  timbers  can 


32  CALIFORNIA    STATE    MINING    BUREAU. 

sustain,  and  a  single  line  of  sets  once  forced  out  of  position  renders  the 
remaining  sets  less  secure  than  before,  and  general  collapse  results; 
and  most  miners  are  familiar  with  the  dangers  and  extraordinary 
expense  incident  to  the  recovery  of  a  caved  stope  and  the  extraction  of 
the  shattered  masses  of  ore  from  the  zone  above  the  cave.  In  veins 
having  vertical  walls  the  danger  of  caves  is  much  lessened,  but  the 
mines  of  the  California  Gold  Belt  dip  at  all  angles  ranging  between  30 
and  85  degrees,  the  greater  number  being  between  45  and  70  degrees,  below 
the  plane  of  the  horizon.  This  being  the  case,  the  pressure  upon  timber 
sets  is  exerted  diagonally  and  not  directly  downward  upon  the  posts  of 
the  sets.  Naturally  this  renders  the  square,  or  rectangular,  sets  less 
capable  of  sustaining  the  weight  and  pressure.  In  some  mines  diagonal 
braces  are  set  in  to  take  this  hanging-wall  pressure  more  directly,  but 
timber  will  not  hold  it. 

In  consideration  of  the  above  facts,  the  absolute  necessity  of  filling 
becomes  apparent,  and  the  necessary  preparations  to  this  end  should 
always  be  promptly  made  in  order  that  the  filling  of  the  stopes  be  not 
too  long  delayed.  Filling  must  be  carried  on  contemporaneously  with 
ore  extraction;  and  in  stoping,  the  excavations  should  be  carried 
upward  in  sections  of  relatively  small  superficial  area,  the  filling  being 
packed  as  close  to  the  back  of  the  stope  as  possible.  Where  the  veins 
do  not  greatly  exceed  15  feet  in  width,  the  conditions  are  essentially 
changed,  as  in  such  cases  the  stopes  may  be  timbered  with  stulls  set 
slightly  above  a  right  angle  to  the  dip  of  the  walls.  Most  mines,  where 
the  walls  are  sufiiciently  firm,  are  timbered  in  this  manner  when  the 
distance  between  walls  admits  of  it.  The  conditions  are  so  variable  in 
these  different  mines,  and  often  in  different  parts  of  the  same  mine, 
that  the  methods  of  timbering  embrace  almost  every  phase  known  in 
practice.  The  various  methods  of  timbering  employed  in  California 
mines  and  elsewhere  were  described  and  illustrated  by  the  writer  in 
Bulletin  No.  2  of  the  California  State  Mining  Bureau,  February,  1896. 
See  also  method  of  stoping  and  filling  at  Eagle-Shawmut  Mine,  Tuolumne 
County,  in  this  bulletin. 

Drainage. — A  very  important  factor  in  the  economy  of  mining  is  the 
water  encountered  in  the  underground  workings,  and  an  ever-present 
question  is  the  most  inexpensive  method  of  removing  this  incoming 
water  from  the  mine.  It  is  accomplished  in  three  ways: — by  natural 
drainage  through  tunnels;  by  means  of  pumps,  or  by  bailing.  This 
subject  has  been  exhaustively  treated  in  Bulletin  No.  9  of  the  State 
Mining  Bureau,  by  Hans  C.  Behr,  M.E.,  and  it  is  unnecessary  to  more 
than  refer  to  it  here.  On  the  Central  Gold  Belt,  and  in  fact  throughout 
California,  the  large  majority  of  mines  bail  water  from  sumps  at  the 
bottom  of  the  shafts,  or  from  tanks  situated  at  various  levels,  where 
water  descending  from  the  surface  and  upper  levels  is  caught. 


i 


THE    MOTHER    LODE    REGION — METHODS    OF    MINING.  33 

Where  the  inflow  of  water  is  large,  and  the  shafts  are  poorly  equipped 
with  hoisting  machinery,  with  crooked,  rough  tracks  or  skids,  the  prob- 
lem of  bailing  water,  hoisting  ore  and  waste,  and  carrying  on  develop- 
ment work — particularly  that  of  sinking  in  the  shaft — becomes  a  serious 
one,  and  sometimes  it  necessitates  shutting  down  all  work  in  the  mine 
except  that  of  sinking.  Where  this  very  undesirable  combination  of 
conditions  is  found,  steam  pumps  are  the  most  satisfactory,  and  it  may 
be  said  that  there  is  a  growing  tendency  to  the  more  extensive  employ- 
ment of  steam  pumps  in  mines  of  the  Pacific  Coast.  In  many  cases 
steam  pumps  are  found  replacing  the  Cornish  pumps. 

In  this  connection,  the  following  contribution  will  be  of  interest  to 
mine  managers  generally.  It  was  written  by  request  for  this  bulletin 
by  Mr.  J.  Renshaw,  one  of  the  foremost  hydraulic  engineers  of  the 
United  States,  and  who  has  had  a  very  extensive  experience  in  mine- 
pumping  operations  where  they  were  conducted  on  a  large  scale: 

SOME     OBSERVATIONS    AS    TO    THE    RELATIVE    ADVANTAGES    OF    CORNISH    AND 
DIRECT-ACTING  DUPLEX  PUMPS  FOR  PERMANENT  MINE  PUMPING. 

By  Mr.  J.  Renshaw,  of  Denver,  Colorado. 

(Written  by  request  for  this  Bulletin.) 

The  following  comparisons  of  the  relative  advantages  of  the  higher  grades  of  direct- 
acting,  duplex  steam  pumps  as  compared  with  the  old  and  well-tried  Cornish  system, 
refer  to  permanent  pumping  plants  for  mines  in  which  the  water  is  below  the  tempera- 
ture of  about  70°  or  75°  Fahr.  When  the  water  is  above  that  temperature,  it  is  evident 
that  the  exhaust  steam  from  the  direct-acting  steam  pumps  cannot  be  advantageously 
disposed  of,  and  either  the  Cornish  pump,  or  some  other  plan  in  which  the  motive 
power  is  located  at  the  surface,  must  be  used. 

Up  to  1878  some  one  of  the  various  modifications  of  the  Cornish  pump  was  exclu- 
sively used  both  in  Europe  and  in  this  country.  In  that  year,  a  simple  cylinder,  non- 
condensing,  single-plunger  pump  at  the  Ontario  Mine,  Utah,  with  12-inch  plungers, 
24-inch  stroke,  and  500  feet  vertical  lift,  was  altered  into  a  compound,  condensing  pump 
by  the  addition  of  an  expansion  cylinder  and  a  spool-shaped  bushing  put  in  the 
original  cylinder,  the  space  between  the  original  bore  and  the  outside  of  the  liushing 
forming  a  steam  jacket.  This  pump  was,  we  believe,  the  first  attempt  toward  a  higher 
grade  direct-acting  steam  pump  located  in  lower  workings  for  permanent  mine  pump- 
ing. It  was  thoroughly  tested,  first  by  the  writer  and  then  by  the  designer  of  a  Cornish 
pump  which  had  been  selected  by  the  writer  to  be  put  in,  should  the  other  not  prove 
economical.  It  met  with  strong  opposition,  mainly  from  the  builders  of  the  Cornish 
pumps,  both  in  California  and  the  East,  and  with  much  skepticism  of  Eastern  mine 
operators,  principally,  we  think,  with  the  belief  that  steam  could  not  be  conducted  in 
pipes  a  long  distance  without  a  ruinous  loss  by  condensation,  and  this  idea  held  among 
many  not  familiar  with  the  results  of  the  compound,  direct-acting,  condensing  steam 
pumps  that  had  been  put  in,  until  1884  and  1886,  when  they  were  put  in  a  mine  at 
Leadville  and  in  one  in  Ishpeming,  Mich.,  since  which  time  very  few  Cornish  pumps 
have  been  built  in  this  country. 

In  1882  or  1883,  a  Cornish  pump  was  built  for  the  Ontario  Mine,  which  is  no  doubt  the 
best  example  of  that  style  of  pump  built,  at  least  in  this  country.  The  writer  had  no 
opportunity  to  test  it,  but  the  manager  of  the  mine  said  that  he  thought  it  saved  a  little 
in  steam  over  the  crude,  direct-acting,  condensing  steam  pumps  that  had  been  installed 
in  that  mine.  When  asked  if  he  was  sure  as  to  any  saving  in  steam,  he  replied  that  he 
was  not,  and  later  advised  a  mine  operator  in  Leadville  to  put  in  the  direct-acting, 
duplex  condensing  pvimp  as  against  the  Cornish  pump,  as  the  difference  in  cost  more 
than  balanced  the  possible  saving  in  steam. 
3 — MB 


34  CALIFORNIA    STATE   MINING    BUREAU. 

We  know  of  no  publicly  reported  experiments  having  been  made  to  determine  the 
amount  of  condensation  in  steam  pipes  until  a  series  was  made  by  the  New  England  Board 
of  Underwriters,  and  reported  in  the  transactions  of  the  American  Society  of  Mechan- 
ical Engineers.  The  result  then  had,  on  pipes  covered  with  one  inch  of  hair  felt  and 
that  by  a  thickness  of  burlaps,  coincided  almost  exactly  with  what  we  had  determined 
at  the  Ontario  Mine  with  the  same  thickness  of  hair  felt  covered  with  10-ounce  canvas. 
At  the  Wolftone  Mine  at  Leadville,  the  condensation  in  585  feet  of  4-inch  wrought-iron 
pipe,  covered  with  ^  inch  of  asbestos  paper,  1  inch  of  hair  felt,  and  this  covered  with 
painted  10-ounce  canvas,  was  57.75  cubic  inches  per  minute,  or  8.396  cubic  inches  per 
minute  for  each  hundred  square  feet  of  external  pipe  surface. 

Judging  by  past  experience,  there  is  little  difference  in  "duty"  between  the  best 
examples  of  Cornish  pumps  and  the  best  examples  of  direct-acting,  compound  con- 
densing pumps,  each,  for  say  1000  gallons  per  minute  lifted  1000  feet  vertically. 

With  triple-expansion,  direct-acting,  condensing  pumps  with  the  initial  steam  pres- 
sure at  the  pump  at  140  pounds,  and  the  pump  running  at  say  125  feet  piston  speed,  the 
comparison  would  undoubtedly  be  much  in  favor  of  it  over  the  Cornish  pump. 

There  are,  however,  other  very  important  considerations  to  the  mine  operator  as  to 
the  relative  advantages  of  the  two  systems  of  pumping,  besides  a  little  difference  in  the 
steam  economy.  On  a  basis  of  1000  gallons  lifted  1000  feet  per  minute,  the  installed 
cost  of  the  direct-acting  pump  will  not  reach  10  per  cent  of  that  for  the  Cornish  pump. 
In  most  cases  the  working-out  of  the  mine  beneath  the  foundations  of  the  Cornish 
pump  engine  will,  by  settlement,  throw  it  out  of  line,  it  not  being  a  self-contained 
machine  like  the  direct-acting  pump.    So,  also,  with  the  "pit-work." 

Another  very  important  consideration  is  the  expansibility — if  we  may  so  call  it— of 
the  two  systems.  When  the  size  of  a  Cornish  pump  is  to  be  determined,  a  large  margin 
for  increase  of  water  through  greater  depth  or  side  workings  has  to  be  allowed  for,  and 
what  this  margin  is  to  be  is  difficult  to  determine.  As  a  rule,  but  one  Cornish  pump 
can  be  installed  in  the  one-pump  compartment  of  the  shaft,  and  it  cannot  be  replaced 
bv  another  without  allowing  the  shaft  to  be  flooded ;  and  it  is  a  question  if  it  could  be 
taken  out  as  fast  as  the  water  would  rise.  This  would  depend  upon  the  amount  of 
ground  worked  out.  Frequently  there  is  allowed  a  greater  margin  for  increase  of  water 
than  afterwards  proves  necessary,  either  from  the  ore-body  giving  out,  or  less  water 
being  encountered  than  expected.  The  interest  on  investment,  and  wear  and  tear  of  a 
larger  machine  than  necessary,  are  important  considerations.  Or,  it  may  be  years  be- 
fore the  full  capacity  of  the  pump  is  called  for.  On  the  other  hand,  if  too  small  a  pump 
is  put  in,  a  new  shaft  has  to  be  put  down  in  which  to  install  another  and  larger  pump. 
Thus,  the  size  of  the  pump  has  to  be  determined  once  for  all. 

Not  so,  however,  with  the  direct-acting  pump.  They  need  only  to  be  bought  as  depth 
is  attained  or  increase  of  size  becomes  necessary.  If  the  pump  proves  too  small,  a 
larger  one  may  be  installed  on  the  pump  station  and  the  smaller  one  moved  down  to  a 
lower  level  where  less  ground  has  been  opened,  and  so  on,  making  pump  stations  every 
500  or  1000  feet.  If  the  column  pipe  for  the  first  pump  put  in  is  not  of  sufficient  size 
for  the  larger  pump,  there  is  generally  room  enough  to  put  in  a  larger  one,  and  the 
smaller  pipe  then  used  below  for  the  small  pump.  The  expenditure  for  pumps  may 
thus  be  by  increments  as  needed. 

As  we  have  said,  pump-shaft  compartments  are  seldom  large  enough  to  install  but 
one  Cornish  pump  line,  and  "the  eggs  are  all  in  one  basket";  whereas  with  direct- 
acting  pumps,  two  may  be  installed  in  the  one  station,  both  connected  to  one  column 
pipe  or  each  with  its  own,  and  in  case  of  necessary  repairs,  one  may  be  stopped  and  the 
other  started.    It  is  very  comfortable  for  the  mine  operator  to  feel  thus  secure. 

If  there  are  two  or  more  compartments  to  the  shaft,  one  of  which  is  for  pump,  piping, 
and  ladders,  that  compartment  should  be  well  bratticed  from  the  adjoining  hoisting 
compartment.  The  heat  radiated  from  even  the  well-covered  steam  pipe  tends  to  make 
that  compartment  an  "uptake"  and  the  hoisting  compartment  a  "downtake,"  and 
thus  fairly  good  ventilation  is  to  be  had  in  the  pump  station  or  level. 

We  need  hardly  say  that  it  is  important  to  keep  pipes  and  their  bearers  snugly  to  the 
sides  of  the  shaft,  so  that  there  will  be  left  a  clear  run  for  the  rising  of  warm  or  foul  air. 

When,  through  the  decomposition  of  pyrites  or  other  minerals,  the  water  is  too  hot 
for  the  condensation  of  steam  below,  then  either  compressed  air  may  be  substituted  for 
steam,  electric,  or  rope-driven  power  pumps,  or  the  Cornish  pump  must  be  used.    With 


I 


THE    MOTHER    LODE    REGION THE   COST   OF    MINING.  35 

the  utilization  of  mountain  streams  as  a  source  of  power,  and  either  electricity  or  com- 
pressed air  to  transmit  it,  comes  a  new  feature  in  mine  pumping  which  will  be  more 
and  more  used,  as  in  miost  of  the  metal-mining  locations  the  cost  of  fuel  is  a  "  burning  " 
question.  The  transmission  of  power  to  the  station  pump  by  electricity  would  present 
a  simple  solution  of  the  difficulty  were  it  not  that  the  speed  of  the  pump  has  to  be 
varied,  either  because  of  increase  of  water  by  ground  opened,  or  by  the  seasons  affecting 
the  surface  water.  We  think  this  difficulty  can  be  overcome  without  uselessly  expend- 
ing power. 

The  above  is  given  as  a  summary  of  the  relative  advantages  of  the  two  systems  of 
mine  pumping,  for  a  part  of  which  we  have  to  rely  upon  memory,  but  we  are  substan- 
tially correct. 

The  Diamond  Drill. — In  a  number  of  mines  of  the  Central  Lode  the 
efficiency  and  great  desirability  of  the  diamond  drill  as  a  prospecting 
device  has  been  repeatedly  demonstrated.  It  has  been  used  with  good 
judgment  and  excellent  results  at  the  mines  of  the  Wildman  Company 
at  Sutter  Creek,  and  also  at  the  Baliol  Mine  near  Sutter  Creek,  Amador 
County;  in  the  Lightner  Mine,  Angels,  Calaveras  County,  and  elsewhere; 
and  there  seems  to  be  a  more  general  disposition  to  employ  this  machine 
for  the  purpose  indicated,  as  by  its  means  ore-shoots  may  be  located  at 
a  distance  from  the  main  mine  workings,  either  in  the  hanging  or  foot 
wall,  at  a  minimum  of  cost.  Not  only  is  the  proximity  or  the  absence 
of  ore  demonstrated,  but  the  character  of  the  barren  rock  through  which 
workings  must  be  driven  in  order  to  reach  such  deposits  is  also  ascer- 
tained, and  the  cost  of  development  thus  approximately  determined. 
The  diamond  drill  may  also  be  employed  in  locating  old  workings, 
making  connections  for  ventilation,  and  even  in  draining  old  flooded 
workings.  Its  use  cannot  be  too  highly  commended  in  a  region  where 
there  are  broad  zones  in  which  occur  ore-shoots  scattered  at  irregular 
intervals,  and  this  feature  is  particularly  characteristic  of  large  portions 
of  the  Central  Gold  Belt.  The  diamond  drill  may  also  be  used  to 
advantage  in  both  the  gold  and  copper  mines  of  the  West  Lode. 


THE  COST  OF  MINING. 

Another  consideration  is  the  cost  of  mining.  This  is  something  which 
can  never  arbitrarily  be  determined  until  the  character  of  the  mine  has 
been  demonstrated.  The  width  and  length  of  the  ore-shoot  must  be 
known,  and  the  character  of  the  walls  ascertained.  The  probable 
quantity  of  water  which  will  have  to  be  handled  is  always  problemati- 
cal, and,  as  a  matter  of  course,  the  character  of  the  walls  and  vein 
material  itself  will  determine  the  method  and  expense  of  timbering.  It 
is  not  uncommon  to  hear  it  said  that  in  California  mining  and  milling 
can  be  accomplished,  under  favorable  conditions,  for  less  than  $1  per 
ton,  but  these  conditions  so  rarely  obtain,  even  in  California,  as  to 
scarcely  be  worth  mentioning,  for  they  by  no  means  constitute  or  illus- 
trate the  typical  features  of  California  mining.  There  are  mines  in 
slaty  rocks  not  particularly  hard,  where  the  veins  are  3  to  7  feet  in 


36 


CALIFORNIA   STATE   MINING    BUREAU. 


width,  which,  being  worked  through  tunnels  and  having  free  water 
power,  are  operated  at  a  very  low  cost,  but  even  this  class  of  mines  does 
not  represent  the  majority — indeed,  such  constitute  a  very  small  minority. 
In  the  greater  number  of  mines  in  this  State  operations  are  conducted 
through  shafts,  which  necessarily  increase  the  expense  of  mining.  In 
the  Central  Gold  Belt  the  mines  vary  so  greatly  in  size,  depth,  char- 
acter of  ore  and  wall-rocks,  and  quantity  of  incoming  water,  that  a 
statement  of  cost  would  convey  but  little  information,  and  comparison 
would  be  valueless  unless  accompanied  by  a  complete  knowledge  of 
existing  conditions  and  an  itemized  cost-sheet.  At  a  number  of  larger 
mines  elaborate  cost-sheets  are  kept,  and  to  a  number  of  these  the 
writer  has  been  given  the  freest  access.  The  cost  of  mining  in  the 
larger  mines,  under  ordinary  conditions,  may  be  fairly  represented  by 
the  cost-sheet  of  the  Wildman  Company  at  Sutter  Creek,  which  has 
been  kindly  furnished  by  the  superintendent,  Mr.  John  Ross,  Jr. 

DETAILED  AVERAGE  COST  OF  MINING  ONE  TON  OF  ORE 

For  the  Years  1896,  1897,  1898,  at  the  Mahoney  Mine  of  the  Wildman  Company. 


Total  Cost  for 
134,886  Tons. 


Cost  per 
Ton. 


Timbers 

Spiling -- 

Lumber 

Charcoal 

Candles 

Powder 

Fuse 

Caps 

Water 

Freight- 

Iron 

Steel  and  steel  rails 

Hardware 

Oil - 

Grease  and  tar 

Coal 

Miscellaneous 

Power-drill  machinery 

Surveying 

Cement -. 

Insurance .-. 

Taxes 

Wire  rope -- 

Office  supplies.-- -. 

Superintendence  and  labor 


Dollars. 
24,499  18 

4,913  05 

1,017  57 

1,242  01 

1,840  59 

4,386  75 

780  16 

186  05 

7,538  00 

1,338  42 

1,224  24 

1,417  27 

3,139  48 

775  37 

117  27 

229  57 

3,241  69 

2,346  90 

667  50 

15  00 

103  77 

737  63 

636  28 

97  67 

160,003  58 


$222,495  00 


Cents. 
18.163 

3.642 

.755 

.92 

1.365 

3.252 

.578 

.138 

5.589 

.992 

.908 

1.05 

2.328 

.575 

.087 

.170 

2.403 

1.740 

.495 

.011 

.077 

.547 

.472 

.072 

118.621 


164.950 


John  Ross,  Je.,  Superintendent. 


THE    MOTHER    LODE    REGION — THE    COST    OF    MINING. 


37 


DETAILED  AVERAGE  COST  OF  MILLING  ONE  TON  OF  ORE 
For  the  Years  1896,  1897,  1898,  at  the  Mahoney  Mill  of  the  Wildman  Company. 


Total  Cost  for 
]31,901Tous. 


Cost  per 
Ton. 


Shoes..- 

Dies 

Screens 

Quicksilver 

Hardware 

Water  for  power 

Freight 

Cyanide  potassium 

Wood 

Charcoal,  iron,  and  steel 

Oil 

Grease . 

Lumber 

Miscellaneous  and  coal 

Timbers ._- - 

Assay  supplies 

Office  supplies 

Expressage,  bullion 

Hauling  and  loading  sulphurets 

Silver-plating  plates 

Insurance    

Taxes 

Plates 

Superintendence  and  labor 


Dollars. 
2,310  00 

2,078  63 

441  97 

870  14 

1,199  05 

10,699  60 

1,064  00 

162  00 

220  88 

97  74 

63  95 

23  13 

67  34 

1,529  46 

17  95 

516  59 

275  73 

391  16 

2,354  65 

281  50 

423  14 

701  11 

86  49 

16,791  58 


142,667  79 


Cents. 
1.712 

1.541 
.328 
.645 
.889 

7.931 
.789 
.120 
.164 
.073 
.047 
.017 
.050 

1.134 
.013 
.382 
.204 
.290 

1.746 
.208 
.314 
.520 
.064 
12.447 


31.628 


The  above  cost  includes  all  repairs  and  equipment. 

John  Ross,  Jr.,  Superintendent. 

Following  is  the  cost-sheet  of  the  Gwin  Mine,  Calaveras  County,  for 
the  month  of  July,  1900,  which  is  kindly  furnished  by  Mr.  J.  J.  Craw- 
ford, secretary  of  the  company: 


38 


CALIFORNIA    STATE    MINING    BUREAU. 


DETAILED  COST  OF  MINING,  MILLING,  AND    SULPHURETS   AT  THE  GWIN  MINE  FOR 

THE  MONTH  OF  JULY,  1900. 


Mining 


And  Trans- 
porting to  Mill 
7,965  Tons. 


Cost  per  Ton. 


Milling 


8,000  Tons. 


Cost  per  Ton. 


SULPHURETS 

Concentra- 
tion, Trans- 
portation and 
Reduction 
Charges  on 
108. 54o  Tons. 


Cost  per  Ton. 


San  Francisco  office — salaries,  directors'  fees, 

and  expenses 

Management 

Mine  office — salaries  and  expenses.. 

Labor 

Water 

Electric  light 

Timbers 

Lagging 

Wedges 

Lumber 

Powder 

Fuse 

Caps 

Candles 

Drill  steel 

Iron  and  steel. 

Tools  and  implements 

Hardware 

Charcoal 

Oils  and  lubricants 

Shoes  and  dies 

Screens 

Chemicals 

Average  loss  of  quicksilver  of  four  years 

Miscellaneous  supplies. 

Survej'ing 

*Assaying apportioned 

*Blacksmith  shoj) apportioned 

*Pumps  and  repairs apportioned 

*Power  drills  and  repairs apportioned 

Legal  expense 

*  Equipment  and  construction...  apportioned 

§  Development apportioned 

Taxes apportioned 

Stable  and  animals apportioned 

Compressor — labor  and  supplies 

*  Compressor apportioned 

*Telephone  line apportioned 

*General  improvements apportioned 

Hauling  sulphurets  and  back  freight  on  sacks. 
Reduction   charges  and  railroad   freight  on 

sulphurets 


Total  cost  per  ton 

For  purpose  of  comparison,  following  items 
may  be  transferred  from  "Sulphurets"  to 
"Milling "  column : 

Labor 

Water 

Electric  light.. 

Miscellaneous  supplies .__ 

Assaying 


Total . 


$   cts. 

.0082 
.0314 
.0129 
1.3886 
.0650 
.0013 
.2754 
.0692 
.0103 
.0050 
.0470 
.0080 
.0020 
.0335 
.0085 
.0014 
.0055 
.0201 


.0035 


.0072 
.0008 
.0341 
.0301 
.0017 
.0025 
.0413 
.0045 
.0370 
.0082 
.0272 
.0210 
.0012 
.0100 


$2.2236 


cts. 

.0084 
.0313 
.0075 
.0653 
.0875 
.0022 


.0031 


.0013 

^6065 
.0003 
.0017 
.0600 
.0007 
.0002 
.0070 
.0020 

^0034 
.0053 


.0006 
.0665 

"oosi 

.0006 


.0004 
.0038 


^    cts. 


3.418 
.746 
.051 


.275 
^212 


2.203 
9.491 


$0.3677 


.0464 
.0100 
.0007 
.0037 
.0028 


.4313 


$16,396 


$11,694 


*Because  of  the  deterioration  of  the  machinery,  etc.,  represented  by  these  accounts, 
one  per  cent  per  month  of  their  cost  and  repairs  is  inserted  in  this  report. 

§The  development  is  apportioned  according  to  the  estimated  life  of  that  part  of  the 
mine  affected  by  it. 


THE    MOTHER    LODE    REGION — MINING    MACHINERY.  39 

At  the  Kennedy  Mine,  Jackson,  Amador  County,  it  may  be  stated 
without  particular  reference  to  detail,  that  the  cost  of  mining,  milling, 
and  all  development  work,  including  the  new  vertical  shaft  and  expense 
of  conducting  chlorination  works,  is  about  $5  per  ton.  The  details  of 
the  Kennedy  cost-sheet  are  not  available  for  publication,  as  the  com- 
pany does  not  carry  their  cost-sheet  out  in  all  its  minutia,  being  satis- 
fied with  more  general  statements  of  cost  and  profit,  but  it  may  be  stated 
that  the  great  apparent  discrepancy  as  compared  with  that  of  the  Wild- 
man  Company's  sheet  is  due  to  the  extremely  unlike  conditions  obtaining 
in  these  two  mines,  which  are  not  more  than  two  miles  apart.  The 
Kennedy  vein  is  much  smaller  than  the  great  ore-shoots  at  the  Wild- 
man,  but  in  the  former  they  are  seldom  without  heavy  swelling  ground, 
which,  under  the  system  of  mining  carried  on  for  years  at  the  Kennedy 
and  other  similar  mines,  requires  constant  relief  and  frequent  retim- 
bering.  This  comparison  is  made  merely  for  the  purpose  of  showing 
that  comparisons  of  cost  without  a  complete  knowledge  of  the  condi- 
tions affecting  such  cost,  are  practically  meaningless,  and  are  unjust  to 
the  mine  managers  who  are  willing  to  furnish  such  figures. 

It  should  be  remembered  in  the  case  of  the  Wildman  Company's 
sheet  that  it  includes  the  years  1896-97-98,  but  does  not  include  the 
years  1899-1900.  Within  the  past  two  years  there  has  been  a  very 
material  advance  in  the  cost  of  many  mining  supplies  and  in  mining 
machinery.  The  mine  cost-sheet  would  be  affected  particularly  in  the 
items  of  iron,  steel,  steel  rails,  hardware,  power-drill  machinery,  wire 
ropes,  etc.,  and  the  mill  sheet  would  show  a  probable  increase  in  cost  of 
shoes,  dies,  screens,  quicksilver,  hardware,  iron,  and  steel.  This  increase 
in  cost  of  the  items  enumerated  would  raise  the  cost  of  both  mining 
and  milling,  and  as  a  matter  of  course,  would  affect  all  other  mines  in 
proportion  to  the  magnitude  of  their  operations.  At  those  mines 
treating  the  largest  quantity  of  ore  per  stamp  the  milling  cost  would  be 
lowest,  and  at  those  mines  hoisting  the  largest  tonnage  of  ore  to  the 
number  of  men  employed  the  mining  cost  would  be  lowest.  Ordinarily, 
in  the  larger  mines,  the  cost  of  timbering  ranges  from  30  cents  to  50 
cents  per  ton  of  ore  extracted. 


MINING  MACHINERY. 

There  is  found  in  the  Gold  Belt  a  great  diversity  of  mining  machinery 
from  the  crude  windlass  to  magnificent  plants  costing  many  thou- 
sands of  dollars.  When  it  is  determined  to  purchase  a  hoisting  plant, 
it  is  always  advisable  to  select  such  machinery  as  the  conditions  under 
which  it  is  to  work,  and  the  object  desired  to  be  accomplished,  shall 
justify.     When  it  is  the  intention  to  sink  a  shaft  to  great  depth,  it  is 


40  CALIFORNIA    STATE    MINING    BUREAU. 

the  best  policy  to  purchase  light  machinery  at  first,  and  at  the  depth  of 
a  few  hundred  feet,  when  necessary,  to  exchange  this  for  heavier  machin- 
ery, but  nol  heavier  than  seems  absolutely  necessary  to  accomplish 
the  work  in  hand.  Very  heavy  and  expensive  hoisting  gear  is  not 
advisable  for  shaft-sinking,  nor  before  the  mine  has  been  developed  to  a 
stage  indicating  the  necessity  of  such  a  plant  for  the  purpose  of  hoist- 
ing large  quantities  of  rock  within  a  limited  time.  For  instance,  it 
would  scarcely  be  considered  wise  to  equip  a  shaft  through  which  it  is 
expected  to  raise  400  tons  of  ore  daily,  with  machinery  capable  of  hand- 
ling ten  times  that  amount.  Heavy  and  expensive  machinery  is  only 
justifiable  when  there  is  sufficient  work  for  it  to  perform.  There  are, 
usually,  at  least  two  active  periods  in  the  life  of  a  mine,  which  are 
distinctly  separate.  These  are,  first,  the  prospecting  period;  and  second, 
the  productive  operating  period;  though  many  mines  never  pass  the 
first  stage. 

Among  the  large  new  enterprises  in  the  Gold  Belt,  the  operations  of 
the  Mariposa  Commercial  and  Mining  Company,  on  the  Mariposa 
Estate,  are  worthy  of  more  than  passing  notice.  These  people,  with 
probably  the  largest  available  capital  for  mining  operations  in  the 
State,  are  prospecting  five  mines  on  their  property.  Everything  is  being 
done  in  a  thorough,  workmanlike  manner,  at  the  lowest  possible  cost, 
without  the  exercise  of  parsimonious  economy.  The  machinery  in  use 
is  first  class  and  exactly  suited  to  the  work  for  which  it  is  being  used; 
that  is,  prospecting.  When  the  limit  of  utility  of  these  machines  has 
been  reached,  others  of  heavier  design  will  be  substituted,  and  the 
lighter  machines  employed  elsewhere,  but  no  great  outlay  for  plant  will 
be  made  until  the  development  of  the  mines  justifies  it.  In  this  respect, 
at  least,  the  management  of  these  properties  is  entitled  to  great  credit. 


MINE  BELL  SIGNALS. 

It  having  come  to  my  notice  that  in  some  localities  the  legalized  code 
of  mine  bell  signals  is  not  in  use,  it  appears  important  to  call  attention 
to  the  fact  that  the  California  State  Legislature  adopted  a  code  of  mine 
bell  signals  May  1,  1893,  which  should  be  adopted  by  all  mines  regard- 
less of  custom  or  different  practice  elsewhere.  There  is  a  liability 
attached  for  the  non-use  of  the  legal  signal  code.  For  the  benefit  of 
California  miners  the  legal  signal  code  is  here  published. 

California  Code  of  Mine  Bell  Signals. 

1  bell,  to  hoist.     See  Rule  2. 

1  bell,  to  stop,  if  in  motion. 

2  bells,  to  lower.     See  Rule  2. 

3  bells,  man  to  be  hoisted;  run  slow.     See  Rule  2. 


THE    MOTHER    LODE    REGION — MINE    BELL    SIGNALS.  41 

4  bells,  start  pump  if  not  running,  or  stop  pump  if  running. 
1 — 3  bells,  start  or  stop  air-compressor. 

5  bells,  send  down  tools.     See  Rule  4. 

6  bells,  send  down  timbers.     See  Rule  4. 

7  bells,  accident;  move  bucket  or  cage  by  verbal  orders  only. 
1 — 4  bells,  foreman  wanted. 

2 — 1 — 1  bells,  done  hoisting  until  called. 

2 — 1 — 2  bells,  done  hoisting  for  the  day. 

2 — 2 — 2  bells,  change  buckets  from  ore  to  water,  or  vice  versa. 

3 — 2 — 1  bells,  ready  to  shoot  in  the  shaft.     See  Rule  3. 

Engineer's  signal  that  he  is  ready  to  hoist  is  to  raise  the  bucket  or 
cage  two  feet  and  lower  it  again.     See  Rule  3. 

Levels  shall  be  designated  and  inserted  in  notice  hereinafter  men- 
tioned.    See  Rule  5. 

For  the  purpose  of  enforcing  and  properly  understanding  the  above 
code  of  signals,  the  following  rules  are  hereby  established : 

Rule  1.     In  giving  signals  make  strokes  on  bell  at  regular  intervals. 

The  bar  ( )  must  take  the  same  time  as  for  one  stroke  of  the  bell, 

and  no  more.  If  timber,  tools,  the  foreman,  bucket,  or  cage  are  wanted 
to  stop  at  any  level  in  the  mine,  signal,  by  number  of  strokes  on  the 
bell,  the  number  of  the  level  first  before  giving  the  signal  for  timber, 
tools,  etc.    Time  between  signals  to  be  double  bars  ( ).    Examples: 

6 5  would  mean  to  stop  at  sixth  level  with  tools. 

4 1 — 1 — 1 1  would  mean  stop  at  fourth  level,  man  on,  hoist. 

2 1 — 4  would  mean  stop  at  second  level  with  foreman. 

Rule  2.  No  person  must  get  off  or  on  the  bucket  or  cage  while  the 
same  is  in  motion.  When  men  are  to  be  hoisted,  give  the  signal  for 
men.  Men  must  then  get  on  the  bucket  or  cage,  then  give  the  signal  to 
hoist.  Bell  cord  must  be  in  reach  of  the  men  on  the  bucket  or  cage  at 
station. 

Rule  3.  After  signal  "Ready  to  shoot  in  shaft,"  engineer  must  give 
the  signal  when  he  is  ready  to  hoist.  Miners  must  then  give  the  signal 
of  "Men  to  be  hoisted,"  then  "spit  fuse,"  get  into  the  bucket,  and  give 
the  signal  to  hoist. 

Rule  4.  All  timber,  tools,  etc.,  "  longer  than  the  depth  of  the  bucket," 
to  be  hoisted  or  lowered,  must  be  securely  lashed  at  the  upper  end  to  the 
cable.  Miners  must  know  they  will  ride  up  or  down  the  shaft  without 
catching  on  rocks  or  timbers  and  being  thrown  out. 

Rule  5.  The  foreman  will  see  that  one  printed  sheet  of  these  signals 
and  rules  for  each  level  and  one  for  the  engine-room  are  attached  to  a 
board  not  less  than  twelve  inches  wide  by  thirty-six  inches  long,  and 


42  CALIFORNIA    STATE    MINING    BUREAU. 

securely  fasten  the  board  up  where  signals  can  be  easily  read  at  the 
places  above  stated. 

Rule  6.  The  above  signals  and  rules  must  be  obeyed.  Any  violation 
will  be  sufficient  grounds  for  discharging  the  party  or  parties  so  doing. 
No  person,  company,  corporation,  or  individual  operating  any  mine 
within  the  State  of  California  shall  be  responsible  for  accidents  that 
may  happen  to  men  disobeying  the  above  rules  and  signals.  Said 
notice  and  rules  shall  be  signed  by  the  person  or  superintendent  having 
charge  of  the  mine,  who  shall  designate  the  name  of  the  corporation  or 
owner  of  the  mine. 

Section  3  of  the  law  says:  "Any  person  or  company  failing  to  carry 
out  any  of  the  provisions  of  this  Act  shall  be  responsible  for  all  damages 
arising  to  or  incurred  by  any  person  working  in  said  mine  during  the 
time  of  such  failure." 


THE    MOTHER    LODE    REGION — AMADOR   COUNTY.  43 


AMADOR  COUNTY. 


Since  the  publication  of  the  last  report  of  the  State  Mining  Bureau 
on  the  mineral  resources  of  the  State,  Amador  County  has  taken  a 
leading  place  in  the  movement  toward  modern  mining  practice.  The 
old-time  mining  methods,  in  many  cases,  have  been  cast  aside  for  more 
modern  ideas,  and  it  may  be  said  that  a  new  era  in  mining  has  only 
commenced. 

In  this  county  are  a  number  of  the  deepest  mines  in  the  State,  as 
well  as  some  of  the  most  valuable.  Since  the  early  days  of  mining  in 
this  county,  it  has  been  the  common  belief  that  the  essential  feature  of 
a  paying  mine  in  Amador  was  a  contact  of  greenstone  and  black  slate. 
The  development  of  the  last  few  years  has  proven  that  this  is  not  abso- 
lutely necessary,  for  some  of  the  best  ore-shoots  found  in  this  county 
are  in  amphibolite  schist,  and  not  associated  with  any  contact.  Another 
erroneous  impression  has  been  that  all  ore-shoots  must  necessarily  be 
found  in  connection  with  the  black  clay  slates  of  the  Mariposa  beds.  To 
such  an  extent  has  this  belief  obtained,  that  it  was  considered  almost  use- 
less to  look  elsewhere  for  paying  mines.  Investigation  of  the  past  season 
has  demonstrated  beyond  a  doubt  that  the  clay  slates  of  the  Mariposa  beds 
have  little  bearing  upon  the  value  of  the  ore  deposits,  and  that  the 
black  slates  found  associated  with  these  ore  deposits  are  the  result  of 
an  alteration  of  diabase  tuffs,  and  may  usually,  if  not  always,  be 
readily  distinguished  from  the  clay  slates.  Moreover,  the  ore  deposits 
do  not  occur  for  any  considerable  distance  on  the  contact  of  these  slates 
and  the  massive  greenstone,  but  are  independent  of  them  throughout 
the  county.  This  subject  has  been  treated  at  some  length  in  the  open- 
ing paragraphs  of  this  volume. 

Between  the  southern  limits  of  the  town  of  Jackson  and  the  Mokel- 
umne  River  on  the  Central  Gold  Belt,  there  are  at  present  no  mines 
which  are  paying,  although  active  operations  are  in  progress  on  several 
properties  included  in  that  section  and  profitable  mines  may  be 
developed.  The  first  mine,  coming  from  the  Mokelumne  River  north- 
ward, which  may  be  included  in  the  paying  class,  is  the  Zeila  Mine. 
In  this  county,  since  our  last  report,  a  number  of  old  mines  have  been 
reopened,  after  an  idleness  of  years.  The  most  important  of  these  are 
the  Oneida,  Central  Eureka,  Lincoln,  and  Bunker  Hill,  descriptions  of 
which  will  be  found  in  the  following  pages.  The  Baliol  Mine,  near 
Sutter  Creek,  is  a  new  mine  which  has  been  extensively  equipped  and 
developed  since  the  publication  of  the  last  report. 


44  CALIFORNIA    STATE    MINING    BUREAU. 

Amador  Queen  No.  1. — This  mine  is  1^  miles  south  of  Jackson.  The 
shaft  has  been  sunk  to  a  depth  of  1200  feet,  with  extensive  development 
at  the  160,  300,  500,  1100,  and  1200  foot  levels.  All  of  the  workings  of 
the  mine  are  in  amphibolite  schist.  Heavy  gouges  are  an  important 
and  characteristic  feature  of  this  mine.  There  is  a  broad  zone  of  schist) 
much  foliated  and  contorted,  with  the  frequent  occurrence  of  seams  and 
veins  of  quartz,  with  occasional  high  values;  galena  and  free  gold  ai;e 
often  observed.  Between  the  1100  and  1200  foot  levels  a  new  shoot  of 
ore  has  recently  been  discovered,  which  is  one  of  the  most  promising 
observed  in  the  mine.  The  shaft  in  this  mine  has  two  compartmentsj 
and  is  sunk  at  a  cost  of  about  $30  per  foot.  Power  is  furnished  by 
water  under  a  head  of  270  feet,  and  transmitted  by  Manila  ropes  to  the 

hoist.     There  are  15  men  employed. The  Jackson  Exploration  and 

Development   Company  (Ltd.),  owners.     James   E.  Dye   of  Jackson, 
superintendent. 

Amador  Queen  No.  3. — It  is  1^  miles  south  of  Jackson,  and  west  of 
Amador  Queen  No.  1.  The  mine  is  opened  through  a  cross-cut  tunnel 
run  1000  feet  to  the  vein,  where  a  station  has  been  cut  underground  and 
a  double-reel  hoisting  plant  installed.  It  is  run  by  water  power  from 
a  reservoir  situated  on  the  hill  above,  the  pipe-line  being  conducted 
through  an  old  shaft.  There  is  a  head  of  312  feet  at  the  hoist.  A  three- 
compartment  winze  has  been  sunk  at  a  uniform  angle  below  the  adit) 
the  vein  dipping  irregularly.  In  January  last,  the  shaft  was  down  730 
feet  below  the  tunnel  level.  The  vein  occurs  in  amphibolite  schist,  and 
is  chiefly  interesting  for  the  amount  of  arsenical  sulphide  (mispickel)> 
rich  in  gold,  which  it  contains.  This  ore  is  shipped;  all  work  done  in 
the  mine  is  performed  by  hand,  no  machines  being  in  use.  The  prop- 
erty is  equipped  with  a  20-stamp  mill;  19  men  are  employed. The 

American  Improvement  Company  of  Toledo,  Ohio,  owners.     John  R- 
Philli]3S,  superintendent. 

Anderson  {New  York)  Mine. — It  is  3  miles  southwest  of  Jackson, 
near  Jackson  Creek.  The  mine  consists  of  a  number  of  ore-shoots 
or  mineralized  zones,  which  occur  in  a  dense  aphanitic  rock,  the 
exact  character  of  which  has  not  been  determined — probably  a  diorite- 
porphyrite.  The  ores  are  found  in  the  crushed  portions  of  this  mass, 
and  consist  of  impregnations  of  iron  sulphides,  free  silica,  and  gold- 
The  oxidation  of  these  deposits  has  resulted  in  the  formation  of  silicious 
iron  ores  carrying  free  gold.  The  mine  is  developed  by  means  of  three 
tunnels:  one  a  cross-cut,  900  feet  in  length;  the  second  a  cross-cut  and 
drift,  300  feet;  the  third  a  drift,  150  feet.  A  winze  has  been  sunk  in 
the  latter  70  feet  in  depth,  with  a  cross-cut  100  feet.  In  addition  to 
this  there  are  numerous  superficial  pits  and  open  cuts  along  the  crop- 
pings.  There  is  a  building  for  a  20-stamp  mill  on  the  property.  In 
this  at  one  time  a  Huntington  mill  was  in  use,  in  which  was  crushed 


THE    MOTHER    LODE    REGION AMADOR   COUNTY.  45 

2500  tons  of  this  ore,  but  a  mill  of  this  tj^pe  is  not  well  suited  to  the 
extremely  hard,  dense  ore  found  in  this  mine.  A  ditch  carrying  400 
inches  of  water,  which  at  the  mine  has  300  feet  head,  is  a  portion  of  the 
property. W.  G.  Anderson  of  Jackson,  owner. 

Butte  Mine. — It  is  a  prospect  5  miles  southeast  of  Jackson,  near  Jack- 
son Butte;  is  opened  by  means  of  a  tunnel,  and  has  a  10-stamp  mill. 
A  small  force  at  work.     Not  visited. 

Spagnoli  Mine. — This  is  at  Clinton.  The  property  was  being  operated 
last  spring  by  the  Hobart  Gold  Mining  Company  of  San  Francisco.  It 
has  an  old  inclined  shaft  110  feet  in  depth,  and  a  new  vertical  shaft 
220  feet  in  depth.  The  vein  occurs  in  granite.  The  mine  was  not 
visited. S.  N.  Spagnoli  of  Jackson,  owner. 

Peerless  Mine. — It  is  2  miles  southwest  of  Jackson  and  about  3  miles 
south  of  the  Kennedy  Mine.  An  inclined  shaft  has  been  sunk  at  or 
near  the  contact  of  black  clay  slates  of  the  Mariposa  beds,  Avhich  occur 
on  the  foot-wall  and  a  diabase  tuff  on  the  hanging-wall.  At  the  surface 
was  discovered  a  small  vein  of  quartz,  which  prospected  well  in  gold. 
There  are  10  men  employed. Peerless  Mining  and  Development  Com- 
pany of  Jackson,  owners.     Henry  Osborne  of  Jackson,  superintendent. 

Kirhwood  Mine. — A  new  property  adjoining  the  Peerless  on  the  south. 
It  is  in  the  prospective  stage. 

Zeila  Mine. — It  is  in  the  southern  limits  of  the  town  of  Jackson. 
Since  the  last  report,  the  shaft  has  been  sunk  from  1160  feet,  at  which 
depth  it  had  remained  for  some  years,  to  1506  feet,  the  lowest  level 
being  opened  at  1350  feet.  The  mine  was  first  worked  about  fort\^  years 
ago,  and  continuously  for  the  last  twenty-one  years.  The  property  has 
a  40-stamp  mill,  which  was  worked  steadily  for  fifteen  years,  when  the 
mortars  of  old  style  were  replaced  by  modern  heavy  mortars,  provided 
with  liners,  etc.  A  modification  of  the  Nevada  square-set  system  is 
emplo^'ed  in  timbering  this  mine.  It  is  substantially  the  same  as  that 
used  at  the  Utica  Mine,  Angels,  Calaveras  County,  but  was  first  intro- 
duced in  the  Zeila  Mine. 

The  Zeila  ore-shoot  occurs  as  a  broad  zone  of  amphibolite  schist  and 
quartz,  30  to  40  feet  wide.  The  ground  is  heavy  and  expensive  to  hold. 
Never  a  rich  mine,  it  has  always,  however,  paid  a  small  profit.  Filling 
is  necessary  in  working  this  mine,  and  is  obtained  from  the  vein  and 
also  from  chambers  cut  in  the  hanging-wall.  The  chlorination  works  at 
this  mine  have  been  entirely  replaced  once,  and  the  hearths  renewed 
several  times;  a  hearth  usually  lasts  about  five  years.  The  manager 
states  that  the  average  expense  of  mining  and  milling  at  the  Zeila  is 
about  $3  per  ton.  In  recent  years  a  canvas  plant  has  been  added  to 
handle  the  tailings  from  the  mill.     115  men   are  employed. Zeila 


46  CALIFORNIA   STATE   MINING   BUREAU. 

Mining   Company   of   Jackson,   owners.      W.    F.   Detert   of    Jackson, 
superintendent. 

The  Zeila  Mill. — The  mill,  which  is  under  the  direction  of  B.  F.  Taylor, 
has  40  stamps  which  weigh  818  pounds,  new.  The  rock  is  crushed  at 
the  hoist  with  Blake  breakers  9x15  inches.  The  mill  is  supplied  with 
Hendy  Challenge  feeders.  The  stamps  drop  7-^  inches,  87  times  a 
minute.  The  screen  used  is  No.  16  brass  wire.  The  discharge  is  7^  to 
9  inches  high;  it  is  regulated  by  the  introduction  of  2-inch  differential 
chuck-blocks.  The  capacity  is  4  tons  daily.  There  is  one  inside 
plate  on  the  chuck-block.  The  pulp  from  the  screen  falls  against  a 
splash  board  and  drops  upon  an  iron  plate  (the  lip  of  the  mortar),  from 
which  it  drops  1  inch  to  an  apron  plate  51  inches  wide  by  30  inches  in 
length;  thence  it  passes  to  the  sluice  plates  16  inches  wide  by  120  inches 
in  length.  The  pulp  passes  by  launders  to  the  vanners.  The  free  gold 
constitutes  but  35  per  cent  of  the  values.  The  plates  are  dressed  daily 
and  a  clean-up  made  monthly.  Experiments  have  shown  that  while 
finer  crushing  will  result  in  saving  more  free  gold,  there  is  a  greater  loss 
of  values  in  sulphides,  due  to  sliming  of  the  ore.  The  iron  shoes  and 
dies  last  100  days,  crushing  400  tons  of  ore.  In  the  Zeila  mortars  there 
is  a  tendency  of  the  center  shoes  and  dies  to  wear  more  rapidly  than 
those  at  the  end  of  the  mortar.  Raw  copper  plates  are  used,  and  it  is 
rarely  the  amalgamators  have  any  trouble  with  copper  salts  or  spots  of 
any  kind  on  the  plates  which  have  never  been  silvered.  This  is  con- 
sidered due  to  the  character  of  the  ore,  consisting  largely  of  chlorite 
schist  with  quartz,  and  containing  no  rapidly  decomposing  sulphides. 
Mr.  Tavlor,  mill  foreman,  states  that  but  twice  has  he  ever  detected 
visible  gold  in  the  ore.  The  sulphides  occur  to  the  amount  of  24  per 
cent  and  have  a  value  of  about  $100  per  ton,  which  is  in  strong  contrast 
with  other  mines  where  the  average  value  of  the  ore  is  higher  than  at 
the  Zeila.  At  the  chlorination  works,  7800  pounds  of  sulphides  are 
treated  daily  in  three  charges  of  2600  pounds  each.  The  furnaces  are 
60  X  11  feet,  inside  measurements.     The  Plattner  process  is  employed. 

The  Zeila  Canvas  Plant. — The  slimes  plant  is  located  at  the  mill. 
Owing  to  the  fact  that  the  issue  from  the  mill  is  near  the  creek  level, 
the  tailings  are  elevated  by  a  centrifugal  pump  to  a  height  of  13^  feet  to 
a  hydraulic  sizer  or  separator;  6^  inches  (miner's)  of  water  are  required 
to  run  the  pump  under  a  head  of  150  feet.  The  daily  output  of  tailings 
consists  of  32  inches  of  water  and  about  150  tons  of  sand,  the  output 
of  a  40-stamp  mill.  The  hydraulic  sizer,  which  is  a  modification  of  the 
well-known  German  spitzkasten,  is  an  invention  of  Mr.  Hambric,  who 
is  in  charge  of  the  plant.  The  accompanying  illustration  (Fig.  3)  will 
give  an  idea  of  the  construction  and  operation  of  this  device.  The  pulp 
falling  into  the  separator,  passes  into  the  first  upright  pipe  in  the  box, 
in  which  is  a  smaller  pipe  with  a  jet  of  water  under  pressure.     This 


THE   MOTHER   LODE   REGION — AMADOR   COUNTY. 


47 


causes  a  violent  ebullition  of  the  sands,  the  coarser  particles  of  which 
pass  out  at  the  bottom,  the  finer  rising  from  the  tube,  re-entering  the 
separator  and  passing  onward  to  the  second  pipe,  where  it  undergoes  a 
similar  operation  by  means  of  a  second  hydraulic  jet.  Here  the  sands 
pass  out  at  the  bottom,  the  slimes  rising  as  before  and  passing  out 
through  a  launder  opposite  the  end  at  which  they  enter.  The  coarse 
material  from  the  separator  goes  to  two  canvas  tables,  which  accumu- 
late about  1-i  tons  of  sulphides  per  month;  the  grade  of  these  tables  is 
3  inches  in  1  foot,  which  is  the  heaviest  grade  in  the  plant.  Tailings 
from  these  tables  go  to  waste.     The  finer  pulp  from  the  separator  goes 


The-    ManJ^RIC  6EPAf^ATOF^ 

Zeila  c)Ll^iEs  Plant. 


'^" 


Fig.  3. 


to  the  tables  of  the  main  plant,  which  are  in  a  building  58x140  feet. 
The  plant  consists  of  32  main  tables,  10  x  12  feet,  and  8  auxiliary  tables, 
for  the  purpose  of  taking  the  overflow  when  purifying  the  tables  of  the 
main  plant.  The  grade  of  these  tables  is  1^  inches  to  the  foot.  The 
pulp  is  divided  into  four  equal  portions  outside  the  building,  and  is 
evenly  distributed  on  an  inclined  plane  provided  with  ribs  3  inches 
apart,  ^  inch  deep,  and  ^  inch  wide.  Along  these  channels  the  pulp 
flows  to  the  canvas  tables.  There  are  eight  divisions  at  the  upper  end, 
which  grow  less  in  number  as  each  table  is  passed,  until  the  last  of  the 
series  is  reached,  where  there  is  but  one.     At  the  head  of  each  table  is  a 


Ze.ILA  CaHVa§>  PL-ANT.JacK-sop. 


PlST{^13UT0f^ 

A.    Launde*^    , 

C    ^o/ af  hs-sd  opspt^eader: 
P.     Cleat  aci'bss  bo/, 
t.    5p)asb  board. 
F:    Can/as  -l^blc. 
(3.    $p  reads  17 


Frci.  4. 


C/)NVas  TA3LEr 
Zeiua       /^iuu. 


5  =  Spreader 


Fig.  5. 


THE    MOTHER    LODE    REGION — AMADOR   COUNTY. 


49 


distributing  device  illustrated  in  the  accompanying  sketches  (Figs.  4 
and  5).  Throughout  the  length  of  the  plant  clear-water  pipes  are  pro- 
vided with  faucets  opposite  each  distributer,  and  between  each  of  two 
tables  is  a  hose  for  washing  the  tables.  At  this  plant  the  owners  under- 
took a  series  of  experiments,  of  which  the  chief  feature  was  the 
discontinuance  of  purifying  the  material  concentrated  on  the  canvas,  by 
washing  off  the  lighter  sands  before  collecting  the  Sulphides.  At  this 
writing  (June  10th)  the  result  of  this  experiment  has  not  been 
ascertained.  At  the  foot  of  the  tables  are  two  launders,  one  for  waste, 
the  other  for  sulphides  collected  on  the  tables.  These  are  kept  separate 
by  means  of  a  movable  bridge  or  apron.  The  washings  from  the  tables 
are  re-concentrated  on  a  belt  machine,  1000  pounds  being  reduced  to 
900  pounds.     All  pulp  from  the  tables  is  elevated  by  means  of  two 


HYDf^AULic  Ejectoi^  or  Pump  a+  ZeiLAa)LiMEs  Plant 

JacKson.  -    CaU 
Fig.  6. 

hydraulic  ejectors,  the  construction  and  operation  of  which  is  illus- 
trated in  the  sketch  (Fig.  6).  The  pulp  passes  to  a  box  having  the 
form  of  an  inverted  truncated  pyramid,  4^  feet  square  at  the  top,  18x24 
inches  at  the  bottom,  and  3^  feet  deep.  The  construction  and  operation  of 
this  device  is  shown  in  Fig.  7,  on  p.  50.  As  previously  stated,  the  practice 
of  purifying  at  this  plant  has  been  discontinued;  the  experiment  has 
demonstrated  that  by  sending  the  concentrates  from  the  tables  to  the 
pointed  box  effects  a  saving  of  from  12  to  15  tons  per  month,  but  it  also 
results  in  lowering  the  grade  of  concentrates.  The  economic  result, 
however,  has  not  been  determined.  No.  8  canvas  is  employed  in  this 
plant,  and  lasts  one  year.  Canvas  for  the  complete  plant  costs  $175. 
The  wear  and  tear  of  the  plant  is  stated  to  be  about  $25  per  month;  the 

4 — MB 


50 


CALIFORNIA    STATE   MINING   BUREAU. 


plant  cost  complete  about  $6,500. Groome  &  Hambric  of  Jackson, 

owners. 

Argonaut  Mine. — One  mile  north  of  Jackson,  adjoining  the  Kennedy 
on  the  south.  The  inclined  shaft  commenced  in  1893  has  now  reached 
a  depth  of  1750  feet,  at  which  point  it  was  stopped  by  an  injunction  of 
the  court,  pending  a  settlement  of  litigation  with  the  Kennedy  Com- 
pany. Above  this  level  the  mine  has  produced  a  large  amount  of  ore, 
which  has  been  crushed  in  a  40-stamp  mill  with  large  profit.  The 
shaft  not  being  sunk  on  the  vein,  a  series  of  raises  have  been  driven, 
which  prove  this  vein  to  be  continuous  from  the  surface  croppings  to 


^/^ 


POINTED^OX 


ZetIL-A     c)LIN\&S  Pl/^nIT 
Fig.  7. 


the  lowest  workings.  The  mine  is  equipped  with  a  heavy  hoisting 
plant,  capable  of  working  to  a  depth  of  2000  feet.  It  is  run  by  water, 
the  power  being  communicated  by  means  of  rope  transmission.  The 
litigation  between  the  Argonaut  and  Kennedy  companies,  in  which  the 
former  company  is  plaintiff,  is  still  pending.  The  geology  of  the 
Argonaut,  and  of  the  Kennedy  Mine  adjoining,  will  be  treated  in  a 
separate  paragraph  following  the  description  of  the  Kennedy  Mine. 

There  are  140  men  employed. Argonaut  Mining  Company  of  San 

Francisco,  owners.     J.  B.  Francis  of  Jackson,  superintendent. 

Argonaut  Mill. — The  rock  is  crushed  in  the  breaker  at  the  hoist  and 
delivered  to  the  mill  bins,  from  which  it  passes  by  chutes  to  Challenge 


THE   MOTHER   LODE    REGION — AMADOR   COUNTY.  51 

feeders.  The  mill  is  in  charge  of  Mr.  B.  Taylor.  It  has  40  stamps, 
which  drop  7  inches,  from  90  to  95  times  per  minute.  No.  30  brass  wire 
screen  is  used.  The  height  of  discharge  is  8^  inches,  which  is  kept  as 
nearly  uniform  as  possible  by  the  use  of  several  chuck-blocks.  The 
capacity  of  the  mill  is  somewhat  variable,  owing  to  changing  character- 
istics of  the  ore,  but  it  is  about  3.25  tons  per  stamp  daily.  The  quantity 
of  water  used  in  the  battery  also  varies  with  changes  in  the  ore.  The 
apron  plates  have  a  grade  of  2  inches  to  the  foot,  and  the  sluices  If 
inches  per  foot.  These  are  dressed  daily;  the  mill  is  cleaned  up 
monthly. 

Some  experiments  of  an  interesting  character  were  made  at  this  mill. 
The  pulp  was  passed  through  a  hydraulic  sizer,  the  coarser  material 
being  sent  to  a  Woodbury  bumping-table,  and  the  finer  to  Union  and 
Woodbury  belt  machines.  The  coarse  material  treated  by  the  bumper 
returned  high  values,  and  the  fine  material  from  the  belts  was  of  medium 


iNcuiMeD   Canvas  co/ered 


TA51-E- 


/O     X     II. 


Fig.  8. 

value.  This  probably  represents  the  two  classes  of  sulphide  material 
found  in  this  mine;  a  coarse,  high-grade  sulphide  occurring  in  the 
quartz,  and  a  fine,  low-grade  sulphide  found  in  the  slaty  ores. 
Another  experiment  made  at  this  mill  was  that  of  re-cleaning  all  the 
concentrates  from  fifteen  machines  by  passing  the  concentrates  of  all 
these  machines  over  one  Union  belt  machine,  with  the  result  that  12  to 
15  per  cent  of  low-grade,  silicious  material,  worth  about  $10  per  ton, 
was  segregated  from  the  concentrates,  which  shows  that  previously  a 
large  quantity  of  material  had  been  shipped  away  at  a  loss,  as  it  con- 
tained less  value  than  the  cost  of  transportation  and  treatment.  As  the 
material  thus  segregated  consists  largely  of  quartz  with  gold,  and  a 
small  amount  of  iron  sulphide,  it  would  seem  that  a  considerable  per- 
centage might  be  recovered  by  grinding  the  sands  in  some  sort  of  mill 
or  pan  with  quicksilver. 

The    Argonaut    Slimes    Plant. — Mr.    F.    S.    Groome   has    built   and 
operates   a  slimes  plant  below  the   Argonaut  mill — the  pulp  coming 


52  CALIFORNIA   STATE   MINING    BUREAU. 

directly  from  the  mill  to  hydraulic  separators,  or  spitzkasten,  and  pass- 
ing thence  to  the  distributers,  the  construction  of  which  is  illustrated 
in  the  accompanying  sketch  (Fig.  8).  In  size,  the  tables  of  the  main 
plant  are  8x16  feet.  The  sized  pulp  is  distributed  to  three  sets  of  tables, 
the  coarse  going  to  a  set  of  three  tables;  the  medium,  which  constitutes 
the  larger  portion  of  the  material,  passing  to  sixteen  tables,  and  the 
finest  material  to  a  third  set  of  three  tables.  The  fall  of  the  tables 
treating  the  finest  material  is  If  inches  in  12  inches;  the  grade  of  the 
medium  tables  is  1-|  inches  in  12  inches,  and  that  of  the  coarse  1|  inches 
in  12  inches;  these  grades  are  adjustable.  The  tables  are  covered  with 
No.  8  canvas.  Owing  to  the  topograph}''  of  the  ground,  it  was  not  neces- 
sary to  construct  these  tables  in  a  series  of  steps  lengthwise  of  the  plant, 
as  in  the  case  of  most  plants  of  this  character.  The  canvas  is  placed 
on  the  long  lines  of  tables  in  a  single  piece,  reaching  the  entire  length 
of  the  plant,  tacked  at  the  edges,  and  then  the  entire  floor  is  divided 
into  a  series  of  tables  by  tacking  down  2-inch  strips  at  regular  intervals. 
The  pulp  is  run  for  one  hour  on  the  canvas  table;  it  is  then  shut  off, 
and  clear  water  turned  on  for  about  five  minutes,  when  the  sulphides 
are  removed  by  means  of  a  hose,  usually  taking  one  minute  to  the  table. 
It  takes  one  man  forty-five  minutes  to  make  a  complete  round,  and 
about  fifteen  minutes  to  look  after  the  outside  machines.  In  this  plant, 
as  at  all  others,  at  the  foot  of  the  tables  is  a  double  launder — one  to 
carry  the  waste  tailings,  the  other  to  carry  the  concentrates  accumu- 
lating upon  and  washed  from  the  tables.  The  concentrates  from  the 
tables  are  sent  to  an  agitator,  which  re-sizes  the  material,  the  finer 
going  to  additional  tables  having  a  grade  of  1-^  inches  in  12,  the  coarser 
material  going  to  a  belt  concentrator,  the  tailings  from  which  are 
pumped  to  an  outside  table  24  feet  in  length,  the  overflow  from  which 
goes  to  a  second  set  of  three  tables.  The  changes  in  the  ore  necessitate 
slight  modifications  in  the  treatment.  About  125  tons  of  material  are 
treated  daily.  Of  the  values  that  come  from  the  mill,  contained  in  the 
tailings,  about  35  per  cent  is  actually  saved,  65  per  cent  escaping  in  the 
coarse  quartz  sand,  the  gold  being  evidently  bound  up  in  the  quartz 
grains,  Avhich  would  require  a  finer  crusher  to  liberate  it;  but  attempts 
made  heretofore  to  save  this  gold  at  a  profit  have  proven  abortive.  It 
would  seem,  however,  that  if  this  material  were  crushed  in  a  mill  of 
proper  construction,  operated  at  a  minimum  cost  of  power,  it  might  yet 
afford  a  small  profit.  In  the  construction  of  this  plant,  green  redwood 
was  employed.  The  foundations  were  firmly  bedded,  and  the  entire 
plant  constructed  with  greatest  care. 

Kennedy  Mine. — It  is  1  mile  north  of  Jackson,  adjoining  the  Argo- 
naut on  the  north.  This  property  has  been  repeatedly  described  in 
former  reports  of  the  State  Mining  Bureau,  but  as  it  is  one  of  the  most 
prominent  mines  in  the  State,  it  merits  further  mention.    Th6  mine  has 


THE   MOTHER    LODE    REGION — AMADOR    COUNTY,  53 

been  worked  continuously  since  1885,  when  work  was  resumed  at  a 
depth  of  750  feet,  to  its  present  depth  of  2300  feet  vertical.  About 
36,000  tons  of  ore  have  been  crushed  annually  for  the  past  fourteen 
years,  at  an  approximate  cost  of  $4.50  to  $5.00  per  ton,  which  includes 
the  cost  of  mining,  supplies,  insurance,  taxes,  superintendence,  purchase 
of  property,  dead  work,  and  new  work.  This  excessive  cost  is  due  largely 
to  the  heavy  swelling  ground  and  the  cost  of  keeping  the  mine  open. 
Since  the  last  report,  the  two  main  shafts  have  been  sunk  several  hun- 
dred feet,  and  a  new  vertical  shaft  has  been  started  on  the  hillside  about 
1900  feet  east  of  the  old  workings.  This  shaft,  in  January,  had  reached 
a  depth  of  915  feet ;  at  this  writing  (June  12th),  it  is  over  1300  feet  deep. 
A  cross-cut  is  being  driven  from  the  2100-foot  level  of  the  Kennedy  Mine 
to  connect  with  the  new  vertical  shaft.  The  general  geological  structure 
of  the  mine  is  referred  to  in  a  paragraph  below,  which  also  includes  that 
of  the  Argonaut  Mine  adjoining. 

The  distribution  of  ore-shoots  in  the  Kennedy-Argonaut  vein  is  of 
considerable  importance  to  miners  along  the  Gold  Belt,  as  in  these 
extensive  workings  it  has  been  shown  that  ore-bodies  are  not  absolutely 
continuous,  either  longitudinally  or  in  depth,  and  that  workings 
can  be  driven  over  the  top  and  along  either  side  of  an  ore-shoot,  and 
beneath  it,  in  fact  completely  surrounding  it,  in  a  barren  fissure.  There 
are  ore- shoots  in  the  Kennedy  Mine  that  do  not  approach  within  sev- 
eral hundred  feet  of  the  surface.  On  the  2100-foot  level  a  new  shoot 
was  recently  discovered  which  started  on  the  west  or  foot  wall  (diabase), 
dipping  at  an  angle  of  approximately  40  degrees  eastward  with  a  trend 
to  the  southward,  which  is  contrary  to  the  usual  trend  of  ore-shoots  in 
this  mine.  The  main  north  shoot  is  wholly  distinct  and  separate  from 
that  on  the  south,  and  it  is  also  distinctly  different  in  character.  At  the 
south  end  of  the  south  shoot,  several  small  veins  come  in  from  the  hang- 
ing-wall side,  uniting  with  the  main  fissure,  and  these  gradually  build 
up  the  large  south  ore-body. 

The  principal  feature  of  interest  at  the  Kennedy  Mine  at  present  is 
the  new  east  shaft.  The  object  of  this  expensive  piece  of  work  is  to 
make  the  large  bodies  of  low-grade  ore  exposed  by  development  in  the 
mine  available  at  a  decreased  cost.  This  shaft  has  been  sunk  through 
hard  greenstone  at  a  rate  approaching  three  feet  per  day.  This  was 
accomplished  by  the  use  of  four  machine  drills,  working  three  shifts. 
Arrangements  were  so  made  that  the  timber  gang  could  work  uninter- 
ruptedly while  drilling  was  in  progress  below.  The  machines  are  set 
on  two  bars  disposed  near  the  end  of  the  shaft,  and  after  having  been 
set  in  place  a  full  round  of  holes  is  put  in,  from  28  to  35  in  number, 
without  taking  down  the  machines.  The  holes  are  drilled  from  5  to  6 
feet  vertically.     The  manner  of  pointing  these  holes  is  shown  in  the 


54 


CALIFORNIA   STATE   MINING   BUREAU. 


accompanying  diagram  (Fig.  9).  There  is  no  hand-drilling,  all  work 
of  squaring-up,  etc.,  being  done  with  machines.  In  this  shaft  26  men 
are  employed.  The  shaft  is  timbered  throughout  with  12x12  Oregon 
pine;  sets  5  feet  from  center  to  center  near  the  top,  and  in  the  lower 
portion  6  feet  from  center  to  center.  The  accompanying  illustration 
(Fig.  10)  shows  the  relation  of  the  strike  of  the  rocks  to  the  position  of 
the  shaft.  (Notice  also  the  strike  of  rocks  in  the  Oneida  and  Wildman 
shafts  in  this  county — see  Figs.  14  and  21.) 

An  unusual  feature  in  the  new  Kennedy  shaft,  not  often  found  in 
shafts  sunk  in  hard  rock,  is  the  bridge  used  in  timbering;  this  is  illus- 
trated in  the  accompanying  sketches  (Figs.  11  and  12).  It  was  claimed 
by  Mr.  George  W.  C.  Glass,  who  was  in  charge  of  this  work,  that  this 


''  ''  !  \  \  ^ 

/        »      t       V        \  N 


/  -    I    / 


I  /    V 


Sh^ETCM    sho^'ns    rrjanner  of  jDlac'inp  MAcHiNEr-f\ouES 

in    h\ENr4EOy   i>HAFT. 

Fig.  9. 

method  of  shaft-timbering  greatly  expedited  matters  and  was  less 
expensive  than  by  the  ordinary  method.  This  manner  of  timbering 
shafts  is  not  novel,  but  is  usually  employed  in  soft  and  not  in  hard 
ground;  but  as  the  bridges  have  been  carried  from  top  to  bottom  in 
this  shaft,  and  as  good  headway  has  been  made  throughout,  it  is  prob- 
able that  this  method  has  given  entire  satisfaction  in  this  instance. 

The  Kennedy  Mill. — This  mill  contains  40  stamps,  and  is  in  charge 
of  Mr.  Webb  Smith.  The  monthly  capacity  is  about  4,000  tons.  The 
stamps  drop  7-5  inches  95  times  per  minute.  The  height  of  discharge  is 
from  8  to  10  inches,  three  differential  chuck-blocks  being  employed  to 
keep  these  as  nearly  uniform  as  possible.  The  grade  of  the  plates  is  1^ 
inches   to    12;    24-mesh    brass    wire    screen    is    used   in    the    battery, 


THE    MOTHER   LODE    REGION — AMADOR   COUNTY. 


55 


formerly  30-mesh.  The  amount  of  water  employed  in  the  battery  is 
variable,  depending  on  the  character  of  the  ore.  Cast-iron,  chilled, 
manganese,  chrome,  and  hammered  steel  shoes  and  dies  have  been  used 
in  this  mill.  The  steel  shoes  and  dies  have  given  the  best  satisfaction; 
the  iron  shoes  last  about  50  days,  the  steel  95  days,  the  latter  crushing 
about  340  tons  of  rock.  The  plates  are  dressed  daily,  and  the  general 
clean-up  is  made  monthly.  There  are  24  Frue  vanners  in  use.  The 
sulphides  collected  on  these  machines  are  treated  in  the  chlorination 
works  at  the  mine,  having  a  daily  capacity  of  Si  tons.  The  average 
saving  is  about  94^  per  cent,  and  the  cost  is  said  to  be  $7  per  ton, 
paying  high  salaries  to  experienced  men. 

The  mortars  used  in  the  Kennedy  mill  were  formerly  of  a  wide  type 
with  double  discharge,  the  rear  discharge  being  closed  for  gold  milling. 
These  have  all  been  replaced  by  narrow,  lined  mortars,  designed  by  Mr- 


5KE.TCH-  sy^owino     STf^lK&of    P'OF^AOt^TIOW  across 
HCennEDY  VeRTiC-AL  q^Ht^FT 

Fig.  10. 

Webb  Smith,  the  mill  foreman.     The  mortars  are  lined  throughout,  and 
have  a  plate  on  the  feed  lip  which  may  be  replaced  when  worn.     There 

are  150  men  employed. Kennedy  Mining  and  Milling  Company  of 

San  Francisco,  owners.     J.  F.  Parks,  superintendent. 

Kennedy  Slimes  Plant. — All  the  tailings  from  the  Kennedy  mill  go  to 
a  slimes  plant,  one  of  the  first  built  and  successfully  operated  on  the 
Gold  Belt.  The  design  is  that  of  Ct.  G.  Gates  of  Jackson,  who  has  car- 
ried the  concentration  of  slimes  to  as  near  perfection  as  may  be  wished. 
Mr.  Gates  has  also  designed  an  end-shake  belt  concentrator  which  does 
splendid  work  on  slimes.  This  machine  is  used  in  recleaning  the  con- 
centrates from  the  canvas  tables.  The  Gates  plant  is  described  at  length 
in  Bulletin  No.  6,  "  California  Mill  Practices,"  by  E.  B.  Preston.  Since 
the  publication  of  that  bulletin,  Mr.  Gates  has  made  no  material  change 
in  the  design  of  his  plant  or  method  of  operating,  although  the  plant 
has  been  entirely  rebuilt.  In  its  general  features  it  is  similar  to  that  at 
the  Zeila  Mine. G.  G.  Gates  of  Jackson,  Cal.,  owner. 


56 


CALIFORNIA   STATE    MINING    BUREAU. 


GEOLOGY    OP   ARGONAUT-KENNEDY   VEIN. 

In  the  Argonaut  and  Kennedy  mines  is  found  a  perfect  example  of 
that  class  of  mineral  deposit  known  as,  and  called,  a  "true  fissure  "  vein. 


-S'£>C7/<i/S^ 


^  im^Aj.^^^^ 


y 


(Q 


TJit/-7c^      CTA/ ^ 


— -J 


_Vr>o/^ 


(Q 


^■^c7/y^  /■cy 


«Q 


'5    cQ 


i< 


«o 


^^3C7/^/cr 


-^^hf-Tcf    cy/^^ 


o^^ 


^~MFW^r#^^ 


S>  C7f^f? 


By  the  term  "  true  fissure"  is  meant  a  vein  or  fissure  which  cuts  through 
rock  formations  of  either  similar  or  unlike  character,  wholly  independ- 
ent of  either  the  dip  or  the  strike  of  the  rocks  which  form  the  walls  of 


THE    MOTHER    LODE    REGION — AMADOR    COUNTY. 


57 


the  vein.  Veins  of  undoubted  fissure  type  do  occur,  however,  which 
conform  with  strike  or  dip  of  the  wall  rocks,  and  in  some  instances  with 
both. 

That  the  Argonaut  vein  is  persistent  for  thousands  of  feet  in  both 
strike  and  dip  is  abundantly  proven  in  the  extensive  workings  of  the 
Argonaut  and  Kennedy  mines,  the  connection  of  their  levels  at  numer- 
ous points  showing  clearly  the  identity  and  continuity  of  the  vein  in 
these  mines. 

The  geology  of  the  vein  is  very  simple  and  may  be  briefly  stated.  That 
geological  horizon  known  as  the  "Mariposa  Beds"  (U.  S.  Geological 
Survey),  which  consists  of   deposits  of  clay  slate  and  altered  diabase 


Vei^tical  Section 

at  corrjer    of 


N 


Posl- 


PlG.   12. 


tuff,  is  found  intruded  by  dike-like  masses  of  diabase.  These  dikes  are 
of  varying  width,  and  appear  to  have  been  thrust  in  from  the  north- 
ward, where,  at  a  distance  of  1000  feet  or  thereabouts,  to  the  northward- 
of  the  Argonaut  shaft  at  the  base  of  Reservoir  Hill,  the  diabase  seems  to 
have  almost  wholly  displaced  the  slates.  To  the  westward  of  the  most 
westerly  of  these  slate  strips  is  found  a  broad  area  of  typical  diabase 
(No,  18),  mostly  massive  and  granular,  extending  many  thousands  of 
feet  to  the  northward  and  southward. 

When  in  their  normal  position  and  condition,  we  find  the  slates  of  the 
Mariposa  beds  along  the  Gold  Belt  almost  universally  dipping  to  the 
eastward  and  striking  a  few  degrees  west  of  north.     In  the  Argonaut 


58  CALIFORNIA    STATE   MINING    BUREAU. 

Mine  local  disturbances  have  resulted  in  folding,  faulting,  and  crushing 
these  slates,  the  degree  of  foliation  and  alteration  appearing  in  propor- 
tion to  the  amount  of  crushing  and  shearing  to  which  the  rock  has  been 
subjected.  Whether  or  not  the  cleavage  of  the  planes  of  the  slates  are 
coincident  with  the  planes  of  sedimentation  cannot  be  determined,  nor 
is  it  important.  At  Sutter  Creek  it  is  known  that  they  are  not.  (For 
illustration,  see  Fig.  20,  page  67.) 

The  diabase  has  also  shared  in  this  alteration  from  the  same  causes, 
namely,  movement  and  fracture  of  the  rock-masses  due  to  tremendous 
compressive  stress,  resulting  in  a  process  of  crushing  and  shearing  of 
this  hard,  tough,  granular  rock,  and  its  consequent  alteration  to  splintery, 
schistose,  and  slaty  rocks,  with  every  phase  of  transition  from  granular 
normal  diabase  to  chloritic  schist  and  slate.  (Amphibolite  schist,  U.  S. 
G.  S.)  Diabase  when  so  altered  to  a  slaty  condition  forms  the  "gray 
slate  "  of  the  miners.  The  slaty  structure  developed  in  the  tuffs  is  often 
so  perfect  that  in  some  instances,  particularly  when  found  in  the  vicinity 
of  the  black  clay  slates  where  they  have  become  blackened  by  meta- 
morphosing influences,  it  is  extremely  difficult  and  often  impossible  to 
distinguish  one  from  the  other  by  their  physical  appearance.  For  a 
description  of  this  type  of  formation  see  "Schists  and  Metamorphic 
Rocks,"  by  G.  H.  Williams. 

The  vein  can  be  followed  continuously  from  its  apex  in  the  Argonaut 
claim  to  the  lowest  level  of  the  mine  without  break  or  interruption  of 
any  kind.  The  apex  or  upper  portion  of  the  Argonaut  Mine  is  wholly 
in  massive  diabase,  which  is  found  much  decomposed  for  some  distance 
on  either  side  of  the  vein  to  a  depth  of  several  hundred  feet,  but  for 
most  part  retaining  its  massive  structure.  (See  Fig.  13.)  In  proxim- 
ity to  the  vein,  an  alteration  to  a  splintery  or  schistose  condition  may 
often  be  observed,  and  impregnations  of  pyrite  are  of  frequent  occurrence 
where  such  alterations  are  found.  In  the  hanging-wall  diabase  near 
the  surface  are  found  numerous  small  veins  and  seams  of  quartz,  some 
of  which  lie  nearly  parallel  with  the  principal  fissure  plane,  but  the 
greater  number  have  a  westerly  dip  extending  upward  from  the  fissure 
into  the  hanging-wall. 

Similar  seams  and  vein-like  sheets  also  occur  in  the  foot-wall  diabase, 
but  usually  in  less  number.  These  attendant  sheets  and  veins  of  quartz 
are  incidental  to  many  veins  elsewhere,  and  veiy  frequently  contain 
sufficient  valuable  material  to  entitle  them  to  be  included  in  the  zone 
of  pay  rock  together  with  the  main  fissure,  when  the  entire  zone  of 
mineralization  is,  and  very  properly  should  be,  considered  as  a  single 
vein  or  lode.  In  making  an  examination  of  the  vein  structure  and 
wall  rocks  in  a  raise  extending  upward  from  the  470-foot  level  to  the 
adit  (Pioneer  tunnel)  level  of  the  Argonaut  Mine,  geological  conditions 
were  found  to  exist  which  at  once  determined  the  fact  that  the  vein 


THE   MOTHEE    LODE    REGION — AMADOR    COUNTY. 


59 


occupies  a  "fault  fissure,"  the  hanging-wall  having  moved  upward 
relatively  to  the  foot-wall,  constituting  a  "thrust"  or  "reverse"  fault. 
There  may  possibly  have  been  also  a  lateral  movement  along  the  fissure 
plane  to  the  southward,  striations  found  on  the  walls  of  the  vein  dip- 
ping to  the  northward  tending  to  strengthen  this  belief.  The  amount  of 
displacement  as  determined  by  measurement  in  the  raise  is  about  125 

fjncien}-  R/vq^ 


Fig.  13. 

feet.  The  quartz  occurs  along  this  plane  in  a  most  persistent  manner, 
and  is  rarely  absent,  even  for  a  short  distance.  In  width  the  quartz 
varies  from  1  to  2  inches  to  upward  of  30  feet.  Where  for  a  brief 
space  quartz  disappears  in  the  raises  above  the  470-foot  level,  the  gouge 
resulting  from  attrition  caused  by  movement  of  these  rock  planes  upon 
each  other,  which  always  accompanies  this  vein,  clearly  indicates  the 


60 


CALIFORNIA    STATE    MINING    BUREAU. 


plane  of  the  fissure.  In  passing  through  these  raises  it  may  be  noticed 
that  where  no  quartz  appears  in  the  fissure  on  one  side  of  the  cutting,  it 
may  usually  be  found  on  the  opposite  side.  No  more  conclusive  evidence 
of  a  continuous  vein  than  the  fact  that  it  occupies  a  fault  plane  could  be 
desired. 

It  may  be  contended  that  this  vein  occupies  a  contact  fissure,  but  the 
conditions  above  described  and  the  abundant  evidence  found  on  the 
several  levels  of  these  mines,  indicate  clearly  that  any  contact  is  of 
purely  local  character,  and  that  the  fissure  is  absolutely  independent  of 
it,  for  the  vein  does  not  conform  for  any  considerable  distance  in  either 
mine,  in  either  strike  or  dip,  to  the  contact  planes  of  the  black  slates 
and  the  diabase,  or  the  schistose  and  slaty  rocks  resulting  from  its 
alteration.  The  dip  of  the  vein  varies  from  a  comparatively  small 
angle  at  the  apex  to  about  67  degrees  from  the  plane  of  the  horizon  in 


-=^  _        —     __      ^^         -AmphMbolite  --Scbisf — ^ — =• 


Sketch    5howi no  relation^    of    c)Tl^lK'E:  of  Af^PHl5014TE-S(;HISri> 
-to  direction    of     NeW  VEf^TlCAl^HAFT.-     ONeiDA  A^INEr— . 

Fig.  14. 

the  lower  levels,  and  in  general  at  a  somewhat  less  angle  than  that 
of  the  inclosing  rocks. 

Oneida  Mine. — It  is  l-j  miles  north  of  Jackson,  adjoining  the 
Kennedy  on  the  north.  Since  the  last  report,  a  new  vertical  shaft  has 
been  sunk  in  the  hanging-wall  to  a  depth  of  2050  feet.  Ground  was 
broken  for  this  shaft  January  13,  1896,  and  February  3,  1896,  the  shaft 
had  reached  a  depth  of  16  feet,  when  work  was  discontinued  for  the 
reason  of  bad  weather.  On  March  9,  1898,  the  shaft  had  reached  a 
depth  of  1550  feet  in  two  years  and  thirty  working  days,  making  a  daily 
average  of  two  feet.  All  this  work  was  done  by  hand,  excepting  during 
a  short  time  when  machines  were  used,  but  their  use  was  discontinued. 
This  shaft  was  laid  out  to  conform  with  the  strike  of  the  formation. 
(See  Fig.  14.)  In  this  respect  it  should  be  compared  with  the  new 
vertical  shaft  of  the  Kennedy  (see  Fig.  10),  and  that  of  the  Wildman  at 


'"'^ggggg*???'*" 


Oneida  Mine,  Amador  County. 


:i 


T4E  Central  Eureka  Mine,  Sutter  Creek,  Amador  County. 


THE    MOTHER    LODE    REGION — AMADOR    COUNTY. 


61 


Sutter  Creek  (see  Fig.  21).  It  is  claimed  that  there  is  considerable 
advantage  gained  in  sinking  the  shaft  at  right  angles  with  the  strike  of 
the  formation  or  diagonally  across  it.  The  timbers  employed  in 
timbering  this  shaft  were  12x12  and  14x14  inches.  The  upper  por- 
tion, in  soft  ground,  is  closely  lagged,  but  the  greater  part  is  without 
lagging. 


Fig.  15. 


n7i9« 


Three  ore-shoots  have  thus  far  been  discovered  in  the  mine,  two  of 
them  near  the  shaft  and  the  third  north  of  it.  The  best  ore  developed 
is  found  on  the  1500-foot  level,  although  ore  has  also  been  developed 
on  the  1700  and  1900  foot  levels.  The  old  incline  shaft  which  was 
sunk  by  the  former  operators  to  a  depth  of  1350  feet  has  been  cleaned 


62 


CALIFORNIA    STATE    MINING    BUREAU. 


out,  a  great  deal  of  it  being  found  in  a  very  bad  condition.  It  was 
probably  one  of  the  most  expensive  and  difficult  jobs  of  opening  an  old 
shaft  that  has  yet  been  found  on  the  lode.  The  new  vertical  shaft  and 
the   old    inclined    shaft   which    will    be   extended   downward,  will   be 


Station  ^^/  c)HAPT.2ooo-ft- Level.  Ooeida  n^iV^e.  Amado.-Co.CAu 


Fig.  16. 


connected  at  various  levels.  The  vein  crosses  the  vertical  shaft  at  the 
1900-foot  station.  Here  the  hanging-wall  is  diabase  and  the  foot-wall 
black  tufaceous  slate.    At  the  station  there  is  a  heavy  gouge  on  the  foot- 


THE    MOTHER    LODE    REGION AMADOR   COUNTY.  63 

wall  side,  and  a  large  vein  of  fine-looking  quartz.  In  the  sump  50  feet 
below  the  2000-foot  level,  and  at  least  50  feet  west  of  the  vein,  a  thin, 
flat  seam  of  quartz  was  found  in  the  diabase  of  the  foot-wall,  containing 
coarse  gold.  This  is  an  unusual  occurrence,  or  at  least  one  not  hereto- 
fore observed  along  the  Lode.  The  method  of  timbering  stations  in  the 
Oneida  Mine  is  shown  in  the  accompanying  illustrations.  (Figs.  15 
and  16.)  • 

A  new  60-stamp  mill  is  in  course  of  construction  at  this  writing, 
early  in  June.  It  will  be  necessary  to  elevate  the  ore  by  some  means, 
probably  an  inclined  tramway,  from  the  shaft  to  the  ore  floor  of  the  mill; 
this  might  have  been  obviated  by  sinking  the  shaft  on  a  ridge  a  short 
distance  eastward  from  the  present  site  of  the  shaft.  A  large,  expensive 
hoisting  plant  forms  a  part  of  the  equipment  of  this  mine.     Forty-three 

men  are  employed. The  Oneida  Gold  Mining  and  Milling  Company 

of    West   Virginia,   owners.     C.  C.  Derby  of  Jackson,  superintendent. 

Since  writing  the  above  the  mill  has  been  completed,  and  20  of  the 
stamps  dropped  early  in  September,  thus  adding  another  producing 
mine  to  those  operating  in  Amador  County. 

South  Eureka  Mine. — This  is  one  mile  south  of  Sutter  Creek,  adjoin- 
ing the  Oneida  on  the  north.  The  north  shaft  is  down  1800  feet,  the 
south  shaft  330  feet,  connected  with  the  600-foot  level  by  a  raise.  This 
vein  occurs  in  black  tufaceous  slates  and  greenstone  schists.  The  ore- 
shoots  trend  to  the  northward  and  vary  greatly  in  size.  The  vein  is 
very  much  disturbed  by  faults  and  flexures,  which  are  difficult  to 
understand  in  the  present  stage  of  development  of  the  mine.  One  per- 
plexing peculiarity  of  this  vein  is  the  finding  of  rich  masses  of  ore  in 
a  large  vein  of  slaty  gouge,  which  have  no  connection  with  any  con- 
tinuous ore-shoot.  Recently  (spring  of  1900),  some  very  good  ore  has 
been  discovered  in  this  mine.  Another  peculiarity  of  the  ore-shoots  is 
that  they  are  richest  in  free  gold  at  the  north  end,  while  the  south  end 
of  the  shoots  are  of  much  lower  grade.  It  seems  characteristic  of  these 
veins  that  while  they  are  broad,  the  values  are  disseminated.  In  many 
of  the  mines  of  this  county,  where  the  veins  exceed  10  or  12  feet  in 
width,  the  best  portion  is  found  next  to  the  foot-wall.  In  some  cases 
from  1  to  10  feet  of  rock  will  be  found  above  the  average  in  grade, 
while  the  remaining  15  to  25  feet  in  thickness  will  be  practically  value- 
less, consisting  principally  of  white,  massive  quartz.  In  this  mine  the 
superintendent  has  arranged  an  ingenious  device  for  hauling  timbers 
into  stopes  above  the  level.  This  consists  of  two  sheaves  set  above  in 
the  raise,  with  one  sheave  at  the  main  gangway.  A  rope  is  passed  over 
these  sheaves  and  a  bucket  attached  at  one  end.  This  bucket  is  hauled 
up  into  the  stopes,  and  a  heavy  timber  attached  to  the  opposite  end  of 
the  rope  down  on  the  level.  When  the  bucket  is  filled  with  ore  it  acts 
as  a  counterbalance,  and  the  timber  can  be  hauled  up  with  comparative 


64  CALIFORNIA    STATE    MINING    BUREAU. 

ease.  The  mine  is  provided  with  a  20-stamp  mill,  run  by  electricity 
furnished  by  the  Standard  Electric  Company.  The  hoist  is  run  by 
water  power  under  180-foot  head,  the  power  being  transmitted  by  means 
of  a  wire  rope  600  feet  long.     There  are  30  men  employed,  except  when 

the  mill  is  running,  when  there  are  from  60  to   70. South  Eureka 

Mining  Company,  owners.     J.  F.  Parks  of  Jackson,  superintendent. 

Central  Eureka  Mine. — This  property  adjoins  the  South  Eureka 
on  the  north,  half  a  mile  south  of  the  town  of  Sutter  Creek.  This 
mine,  after  an  idleness  of  many  years,  was  reopened  by  a  new  company 
in  the  fall  of  1895.  There  were  several  shafts  on  the  property  at  that 
time,  the  deepest  being  the  south  shaft,  down  700  feet.  Since  that  time 
the  shaft  has  been  continued  to  a  depth  of  1700  feet  and  a  number  of 
long  levels  opened.  At  about  the  1000-foot  level,  several  narrow  and 
short  shoots  of  high-grade  ore  were  developed.  As  depth  was  attained 
and  levels  driven  out,  these  ore-shoots  were  found  to  lengthen  and 
increase  in  width  while  maintaining  their  values,  until  in  the  deepest 
portion  of  the  mine  the  several  short  shoots  have  united,  forming  a 
single  long  shoot.  At  this  writing  (January,  1900),  the  Central  Eureka 
Mine  is  one  of  great  promise.  The  vein  is  the  most  simple  in  geological 
structure  of  any  extensively  developed  mine  on  the  Central  Lode.  It 
consists  practically  of  a  single  fissure  cutting  in  strike  and  dip  the 
black  tufaceous  slates  and  amphibolite  schist  which  form  its  walls. 
The  mine  has  certain  peculiarities  which  are  noticeably  persistent. 
One  of  these  is  the  firmness  and  regularity  of  the  hanging-wall.  The 
wall  is  not  absolutely  straight  in  strike,  but  rolls  more  or  less  in  a 
series  of  long  swells.  The  gouge,  which  is  always  found  on  the  foot- 
wall  side,  also  has  a  sinuous  course,  swinging  toward  and  away  from 
the  hanging-wall.  When  at  some  distance  from  the  hanging-wall  little 
or  no  ore  occurs  in  the  fissure,  but  upon  its  approach  to  the  hanging- 
wall  the  long  lenticular  masses  of  quartz  which  constitute  these  ore- 
bodies,  begin  to  form.  Another  feature  of  the  vein  is  found  in  the 
increasing  mineralization  of  the  rock  forming  the  hanging-wall  upon 
nearing  an  ore-shoot.  Although  at  the  time  of  my  visit  no  cross-cuts 
had  been  made  in  the  hanging-wall  country  from  the  lower  levels  of 
this  mine,  there  is  little  doubt  that  considerable  portions  of  the  mineral- 
ized zone  of  the  hanging-wall  will  be  found  to  make  payable  ore, 
although  of  comparatively  low  grade.  A  considerable  quantity  of  the 
ore  taken  from  the  shoots  above  described  has  been  milled,  returning  an 
average  of  about  $70  per  ton.  The  hoist  is  run  by  water  power.  A 
10-stamp  mill  has  been  completed  and  is  in  operation.  The  mill  has 
an  extension  for  10  additional  stamps.  In  September  the  shaft  had 
reached  a  depth  of  1845  feet,  and  the  vein  is  from  1  to  12  feet  in  width 
between  the  1400  and  1800  levels.  A  new  hoist  is  being  put  in,  and  the 
mill,  rockbreaker,  and  exhaust  fan  are  running  by  electricity. Cen- 


s^r-f*:^ 


_^>-.«i**'-"'?'~T''^' 


The  Mahoney  Mine,  Sutter  Creek,  Amador  County. 


Timbering  in  Caving  Ground,  Mahoney  Mine,  Amador  County. 


THE    MOTHER    LODE    REGION — AMADOR   COUNTY.  65 

tral   Eureka    Mining   Company,   owners.     W.   R.   Thomas    of    Sutter 
Creek,  superintendent. 

Wildman-Mahoney  Mine. — This  is  at  Sutter  Creek.  The  property- 
consists  of  the  Wildman,  Mahoney  or  Hector,  and  Stewart  claims,  also 
the  Waechter  ranch  to  the  eastward  of  these  mines  on  which  a  new  vertical 
shaft  is  being  sunk.  The  development. at  present  is  chiefly  confined  to 
the  Wildman  and  Mahoney  claims,  which  join  and  are  operated  through 
two  inclined  shafts.  The  Wildman  is  1300  feet  deep,  the  Mahoney 
1000.  The  1000-foot  level  of  the  Mahoney  is  equivalent  to  the  800-foot 
level  of  the  Wildman.  The  ore-bodies  of  these  mines,  both  great  and 
small,  appear  to  be  confined  to  a  definite  zone  lying  between  two  reefs 
of  Mariposa  clay  slates,  although  these  latter  appear  not  to  be  directly 
associated  with  the  ore-bodies  themselves.  The  zone  included  between 
the  clay  slates  consists  principally  of  amphibolite  schist  and  tufaceous 
black  slates.  ^  In  the  southern  portion  of  the  Wildman  Mine  the  ore 
zone  is  confined  to  narrow  limits,  but  going  northward  it  broadens,  and 
in   the   Mahoney  claim   the   vein   splits   into   two   sections,  the   east 


Good  ore  lying  each  side  of  a  Sfl-diou^e  in  Wildrr^an  H^i^e 

Fig.  17. 

branch  going  into  the  Stewart  claim  and  the  west  into  the  Lmcoln.  The 
idea  seems  to  prevail  that  the  mines  of  the  Gold  Belt  of  Amador  County 
are  simple  fissures,  which  are  easily  followed  and  are  regular  and  per- 
sistent. Just  the  reverse,  however,  is  usually  the  case,  as  the  ore-bodies 
are  found  disturbed  by  faults,  and  often  contorted  and  displaced  in  a 
most  puzzling  manner.  On  the  300-foot  level  of  the  Mahoney  Mine  one 
vein  follows  a  gouge  4  feet  wide,  on  the  hanging-wall  of  which  the  ore 
continues  for  a  distance  of  300  feet;  going  southward  for  some  dis- 
tance the  ore  loses  its  value,  but  undergoes  no  physical  change  that  is 
noteworthy.  Noticing  that  the  gouge  contained  small  masses  of  good 
ore,  from  20  to  400  pounds  in  weight.  Superintendent  Ross  cross-cut 
into  the  foot-wall  and  found  good  ore  in  the  opposite  side.  (See  sketch, 
Fig.  17.)  This  was  the  only  place  known,  up  to  that  time,  where  pay 
ore  was  found  in  the  gouge.  The  ore  found  on  the  foot-wall  side  of  the 
zone  was  15  feet  wide,  but  its  length  has  not  been  determined.  These 
ore-shoots  are  known  to  overlap  25  feet  at  least,  and  probably  much  more. 
Another  instance  of  irregularity  was  noticed  in  the  Mahoney  Mine  30  feet 

5 — MB 


66 


CALIFORNIA    STATE    MINING   BUREAU. 


above  the  900-foot  level,  where  is  found  what  appears  to  be  a  displace- 
ment of  a  banded  vein  15  feet  in  width,  which,  together  with  the  inclosed 
slates,  is  contorted  and  cut  off  abruptly,  the  sheared  end  abutting  against 
a  solid  vein  of  quartz  20  feet  in  thickness.  (See  Fig.  18.)  The  contin- 
uation of  this  faulted  vein  has  not,  as  yet,  been  found  above.  The  slaty 
material  found  underneath  the  banded  vein  is  also  gold-bearing  in  pay- 
ing quantities.  A  stope  on  the'  900-foot  level  of  the  Mahoney  follows 
a  well-defined,  persistent  wall  for  a  long  distance.  This  stope  is  25  feet 
in  width.  A  fissure  crosses  the  ore-shoot  at  an  angle  of  65  degrees,  dip- 
ping south.     Beyond  this  was  found  the  above  described  disturbance. 


I'^AULT   on  900fr  LevE-L.   of  ■tt7e  Ma-HONEY  AAirNE:,SutterCreel<.. 

Fig.  18. 

On  the  1000-foot  level  of  this  mine,  a  stope  follows  what  appears  to  be 
the  wall  above  described,  with  large  ore  deposits  on  either  side  of  the 
wall.  The  wall  takes  a  slight  flexure  to  the  west,  and  the  ore  follows 
the  wall  on  the  foot  side,  while  that  previously  followed  on  the  hanging- 
wall  side  bears  more  to  the  east,  and  a  slate  horse  separates  them.  In 
the  main  level,  the  drift  continues  south,  and  a  new  ore-shoot  comes  in 
from  the  east  or  hanging  wall.  A  diamond-drill  hole  run  west,  here 
passes  through  6  feet  of  slate  and  cuts  3  feet  of  quartz,  which  is  suc- 
ceeded by  22  feet  of  slate  and  6  feet  of  ore.  This  probably  represents 
the  two  branches  of  the  divided  vein.  The  diamond-drill  hole  continues 
for  a  distance  of  204  feet,  where  it  cuts  a  vein  of   good  ore  13  feet 


THE   MOTHER   LODE    REGION — AMADOR   COUNTY. 


67 


thick.     This  may  be  the  downward  extension  of  the  ore  dipping  west- 
erly on  the  level  above,  though  such  a  thing  is  far  from  certain.    In  the 


Amphibolite       Schist     -^-^zz    ^-'   , 


Sketch  of- Vein  in  Wiloman    Ajinet. 

sbov>/i9^  indepei9de9ce    op  Yelrp   and    Contacts 


Fig.  19. 


Wildman  Mine,  on  the  800-foot  level,  is  a  24-foot  ore-body  on  the  slate 
foot-wall.     On  the  1000-foot  level  of  the  Mahoney,  what  is  evidently 


Slaty  ClEAVAGEt  -  Pe\/©lopsd    by  |Dre&=.ure  m  fo\de.d  §)ti'ata_ 
OF-  /''^Af^lPOSA  Beds  -at  i>une\- CreeK.-Arqador  Co-  C-^i-. 

Hof?izoNTAL-  Section 

Fig.  20. 

this  same  ore-bodj  is  developed,  but  it  lies  23  feet  east  of  the  slates 
(Fig.  19).     These  irregularities  are  only  a  few  of  those  which  occur 


68 


CALIFORNIA    STATE   MINING   BUREAU. 


throughout  this  extensive  property,  and  are  simply  mentioned  to  illus- 
trate the  peculiarities  and  irregularities  of  the  ore-deposits.  A  complete 
description  of  the  mine,  taken  by  levels,  would  fill  a  good-sized  volume. 
The  Wildman-Mahoney  Mine  labors  under  great  disadvantage  in  being 
obliged  to  work  through  the  old  inclined  shafts,  that  of  the  Wildman 
Mine  being  particularly  bad,  and  the  cause  of  what  would  be  otherwise 
unnecessary  expense.  The  completion  of  the  new  Emerson  shaft,  below 
described,  will  remedy  this  trouble,  and  the  large  bodies  of  ore,  too  low- 
grade  to  pay  under  existing  conditions,  can  then  be  worked  at  a  profit. 
Fig.  20  illustrates  the  contortion  of  slates  and  the  subsequent  devel- 
opment of  slaty  cleavage  in  Mariposa  beds  at  Sutter  Creek.  The  sketch 
is  of  an  area  20  feet  square. 


c)KETCW  sF^oWi'r^o   fjelaVier^  o^  StriKe  of  forrrjsitoqio  Wildrr]aq 

Sf^afh 

Fig.  21. 

The  Emerson  Shaft. — The  new,  or  Emerson,  shaft,  as  it  is  called,  is 
vertical,  and  is  being  sunk  nearly  1000  feet  east  of  the  present  Wildman 
inclined  shaft.  It  is  calculated  that  it  will  cut  the  Wildman  vein  at  a 
depth  of  between  2300  and  2400  feet.  It  is  difficult  to  give  the  exact 
depth,  as  through  this  section  the  lode  flattens  more  or  less  in  depth. 
It  is  now  down  over  700  feet.  The  ground  passed  through  is  diabase 
and  diabase  tuff,  with  some  very  hard  gray  slate  (altered  diabase),  an 
occasional  seam  of  black  slate  and  stringers  of  barren  quartz.  The  exca- 
vation outside  of  timbers  is  8  x  20  feet,  and  is  made  across  the  stratifi- 
cation of  the  country — that  is,  the  length  of  the  shaft  is  east  and  west. 
(See  Fig.  21.)  Timbers  used  are  all  selected  spruce,  12x14  inches, 
framed  in  the  usual  Comstock  style,  with  the  following  exceptions: 

First,  the  wall-plates  are  placed  with  the  12-inch  side  vertical,  and 
the  dividers  with  the  14-inch  side  vertical.  A  dap  is  cut  ^  inch  deep  in 
the  wall-plate,  top  and  bottom,  for  the  center  posts,  which  leaves  1^-inch 
footing  and  heading  for  the  posts,  as  the  14-inch  side  or  end  of  the 
divider  comes  against  wall-plate  and  posts,  thus  giving  more  strength 


THE   MOTHER   LODE   REGION — AMADOR   COUNTY. 


69 


to  the  wall-plate  and  a  better  footing  for  the  posts  than  would  be  the 
case  if  the  divider  were  of  the  same  width  as  the  wall-plate. 

Second,  as  seen  in  sketch 
of  divider  (see  Fig.  22),  a 
2-inch  filling  piece  is  in- 
serted behind  each  guide, 
which  gives  4  inches  to 
work  on  (in  keeping  guides 
true)  in  case  of  a  squeeze 
in  the  shaft. 

The  sketch  of  section  of 
shaft  (Fig.  23)  shows  a 
small  "service  cage"  in 
the  pump  compartment  for 
the  use  of  foreman  and 
pumpmen.  It  is  to  be  run 
open  on  two  sides,  to  facili- 
tate the  handling  of  long 
lengths  of  pipe.  All  of  the 
pipes  are  set  on  the  side  of 
the  shaft  opposite  this  cage. 
The  ladders  are  each  15 
feet  long,  inclined  over  each 
other,  there  being  a  landing 
at  the  end  of  each  ladder, 
from   center   to   center   of 


Section  ofQuid^sa'^/Oivider 

showing  Filling  Piece- Wildman  Shafh 

Fig.  22. 

The  shaft  sets  are  4  feet  apart,  or  5  feet 
wall-plates.     The   skip   compartments   are 


Fig.  23. 


WlLDA^A/SI       ShAF-T. 


4^  X  4i  feet,  and  the  pump  and  ladder  compartments  4-|  x  5  feet.  The 
wall-plates  and  ends  of  dividers  are  so  framed  that  the  dividers  are 
driven  up  into  place  instead  of  down,  which  prevents  their  being 
knocked  out  by  blasts. 


70 


CALIFORNIA   STATE   MINING   BUREAU. 


It  is  the  intention  to  use  skips  that  will  carry  3  tons  of  ore  at  a  load, 
making  total  weight  of  load  (including  cable  and  skip),  starting  at  a 
depth  of  2500  feet,  about  6  tons.  Foundations  of  stone  and  cement  for 
permanent  headgear  have  been  built  from  bedrock  to  the  level  of  the 
collar  of  the  shaft.     The  temporary  hoist  and  gallows  frame  now  in  use 


WiLDMAH    Mill 

without  ir^stde  Platen*. 


Fi&.  24. 


at  this  shaft  is  so  constructed  and  arranged  that  the  permanent  steel 
head  frame  can  be  erected  over  the  shaft  without  interfering  with  the 
progress  of  work.  The  design  of  the  proposed  steel  headgear  is  by  E 
Chodsko,  of  San  Francisco.  If  erected  this  year  it  will  be  the  first  of  its 
kind  in  California. 


THE   MOTHER   LODE    REGION — AMADOR   COUNTY. 


71 


The  Wildman  Mill. — The  mills  of  the  Wildm  an  Company  are  operated 
with  as  great  care  as  any  in  the  State,  and  merit  a  detailed  description. 
There  are  two  mills,  each  of  40  stamps.  In  the  Wildman  mill  the 
stamps  weigh  850  pounds;  these  drop  from  7  to  9  inches  96  times  per 
minute;  the  guides  are  of  iron;  the  height  of  discharge  is  7^  inches, 
regulated  by  chuck-blocks,  having  a  difference  of  ^  to  2  inches  in  height. 
A  No.  2  punched  tin  screen  is  used.  The  capacity  of  the  mill  had  been 
about  145  tons  per  day  under  the  above  conditions,  but  the  height  of 
discharge  has  been  lowered  not  to  exceed  6  inches  for  the  purpose  of 
experimentation.  This  will  have  a  tendency  to  increase  the  capacity  of 
the  mill.     The  outside   plates  have  a  grade  of  1|  inches  to  the  foot. 


Iron  bar. 


Detaiu. 

Sectional  Plate 

ON   CHUC^^,SLOC^^. 


(^racKct- 


Old  Style  ^(reeM  Pf^A/^t 
Wildr9a9A)ill. 


Detail,. 
/fanner  of  VVed^ir)^  Sc(\EEr(  1>  NJAIN  pT^Af^Er 

Fig.  25. 


There  are  14  Frue  vanners  and  2  Triumph  concentrators  in  use.  The 
ore  contains  about  1  j-q  per  cent  sulphurets,  which  are  shipped  to  Selby's. 
They  formerly  used  11x48  inch  No.  24  Russian  iron  and  cold  rolled 
steel  screens,  diagonal  slot.  Of  these  the  steel  screens  proved  the  most 
durable.  They  now  use  a  No.  2  punched  tin  screen  having  225  holes  to 
the  square  inch.  These  apertures  have  a  slightly  greater  diameter  than 
the  slot  of  the  No.  24  screen.  Formerly  the  screen  was  secured  flush 
with  the  outside  of  the  frame,  which  was  provided  with  an  inside  plate. 
The  screen  frames  are  now  arranged  as  shown  in  the  accompanying 
drawing  (Fig.  24).     The  former  method  is  shown  in  Fig.  25. 

The  Hector  or  Mahoney  Mill. — In  this  mill  there  are  40  stamps,  which 
weigh  950  pounds.    The  height  of  the  drop  is  from  7  to  9  inches  96  times 


72  CALIFORNIA    STATE   MINING   BUREAU. 

a  minute.  The  height  of  discharge  was  formerly  6^  inches,  but  is  now 
from  3^  to  4  inches,  being  adjusted  by  differential  chuck-blocks.  The 
Globe  Iron  Works  guides  are  in  use.  A  No.  2  punched  tin  screen  is 
used,  the  capacity  being  146  tons  per  day.  Chrome-steel  shoes  and  dies 
having  8^  inches  diameter  are  used.  There  are  16  Frue  vanners  in 
the  mill  which  concentrate  the  sulphides,  these  constituting  ly^^j^  per 
cent  of  the  rock.  In  the  Hector  mill  the  pulp  falls  from  the  batteries 
onto  a  4-inch  plate  and  drops  to  a  second  plate  pitching  backward,  falling 
on  the  lip  of  the  mortar  below,  in  front  of  which  is  a  5-inch  plate  with 
a  |-inch  drop  to  the  first  apron  plate  28  inches  wide.  The  inside 
plates  have  been  taken  from  the  mortars  and  every  effort  made  to  in- 
crease the  capacity  of  the  mill,  while  giving  the  most  careful  attention 
to  outside  amalgamation.  Below  the  first  apron  plate,  the  pulp  falls 
into  a  trough  3  inches  wide  and  4^  inches  deep,  discharging  through  ten 
I'inch  auger  holes,  then  to  a  3-inch  board  and  onto  plates  24  inches 
square,  arranged  in  double  parallel  series.  The  pulp  passes  by  two 
drops  to  two  other  sets  of  plates,  at  the  foot  of  which  is  a  mercury  trap. 
Below  the  trap  are  sluice  plates  with  three  drops  of  2  inches  each. 
These  plates  are  12  feet  long,  at  the  lower  end  of  which  a  second  trap  is 
arranged,  from  which  the  pulp  goes  to  the  vanners.  165  men  are  em- 
ployed in  the  mines  and  mills. The  Wildman  Gold  Mining  Company, 

owners.     John  Ross,  Jr.,  of  Sutter  Creek,  superintendent. 

Lincoln  Mine. — It  is  at  Sutter  Creek.  This  property  was  worked  in 
early  days,  a  shaft  being  sunk  807  feet.  To  a  depth  of  350  feet,  or 
thereabouts,  it  is  said  that  the  mine  paid  handsomely.  At  that  depth 
a  fault  intersected  the  vein  and  all  trace  of  it  was  lost.  The  present 
company  re-opened  the  mine  in  the  latter  part  of  1898.  The  old  shaft 
was  repaired,  the  workings  cleaned  out,  and  sinking  resumed  in  Febru- 
ary, 1899.  The  shaft  is  now  1260  feet  in  depth.  On  the  500-foot  level 
a  drift  has  been  extended  several  hundred  feet,  and  a  cross-cut  run  both 
east  and  west  about  200  feet  north  of  the  shaft.  That  portion  east  of 
the  main  gangway  is  in  tufaceous  slate  and  diabase,  and  that  to  the 
westward  passes  through  the  black  tufaceous  slates,  and  then  through  a 
broad  zone  of  hard,  amphibolite  schist,  to  the  black  clay  slates  of  the 
Mariposa  beds  315  feet  west  of  the  gangway.  In  this  cross-cut  are 
exposed  three  ore  veins,  one  of  which  has  been  drifted  for  a  distance  of 
168  feet.  This  vein  is  110  feet  west  of  the  gangway.  A  second  vein  is 
encountered  135  feet  farther  west.  This  vein  is  from  6  to  20  feet  wide, 
and  carries  a  satisfactory  grade  of  pay  rock  consisting  of  quartz  and 
amphibolite  schist  with  disseminated  auriferous  iron  sulphide  and  free 
gold.  It  has  been  developed  by  a  drift  200  feet  long.  The  third  vein 
lies  about  70  feet  to  the  westward  of  the  last-mentioned  vein,  near  the 
contact  of  the  amphibolite  schist  and  the  clay  slate  of  the  Mariposa 
beds.     It  has  not  been  developed  as  yet.     As  there  appeared  to  be 


Lincoln  Mine,  Sctter  Creek,  Amador  County. 


_>^ 


The  Bunker  Hii.l  Mine,  Amador  County. 


THE   MOTHER    LODE    REGION — AMADOR   COUNTY. 


73 


some  doubt  as  to  what  had  occurred  at  the  350-foot  level,  when  the 
mine  was  formerly  operated,  a  careful  examination  of  an  old  abandoned 
level  extending  from  the  shaft  at  400  feet  from  the  surface  was  made  by- 
Superintendent  Voorheis  and  the  writer.  An  investigation  at  this 
point  discovered  the  fact  that  a  fault  fissure  had  dislocated  the  vein. 


Cross  Section-  Lincoln  A^ine:  .  §utferCrecK:-T^+n7ait7  &hafh-_ 

Pig. 26. 

The  fault  strikes  nearly  parallel  with  the  vein,  dipping  to  the  eastward 
at  an  angle  of  about  58  degrees,  and  appears  as  a  zone  of  fracture  and 
movement  4  to  6  feet  in  width.  To  the  eastward  of  this  fault  plane  the 
schists  and  slates  and  the  vein  itself  all  have  an  easterly  dip.  Under- 
neath the  fault  plane,  however,  the  entire  country — schists,  greenstones, 


74  CALIFORNIA    STATE    MINING   BUREAU. 

slates,  and  veins — dips  strongly  to  the  westward.  In  the  west  cross-cut 
north  of  the  shaft  on  the  500-foot  level,  and  in  a  west  cross-cut  south  of 
the  shaft  on  the  same  level,  this  condition  is  clearly  in  evidence.  A 
cross-cut  run  westerly  from  the  shaft  at  the  650-foot  level  shows  the 
formation  to  be  still  pitching  to  the  westward,  though  in  a  cross-cut  at 
the  800-foot  level  it  is  standing  nearly  vertical,  and  on  the  1200-foot 
level  the  formation  has  assumed  nearly  its  normal  easterly  dip  in  the 
neighborhood  of  the  shaft.  On  this  level,  at  the  face  of  the  cross-cut 
275  feet  west  of  the  shaft,  it  has  a  slight  westerly  dip.  These  workings 
show  that  the  entire  formation  lying  to  the  westward  of  the  fault  plane 
has  been  contorted  from  its  normal  position,  having  a  westerly  instead 
of  an  easterly  dip,  although  as  depth  is  attained  the  formations  appear 
to  assume  their  normal  positions.  The  sketch  (Fig.  26)  illustrates  the 
structural  features  of  the  Lincoln  Mine.  All  the  evidence  obtainable 
leads  to  the  belief  that  the  rich  vein  worked  from  the  surface  slipped 
downward  along  the  fault  plane,  and  that  its  further  extension  down- 
ward must  be  sought  in  the  country  lying  to  the  westward  of  the  shaft, 
and  it  is  the  belief  of  the  writer  that  the  cross-cuts  on  the  500-foot  level 
have  intersected  the  vein  which  was  dislocated  by  the  fault  at  the  350- 
foot  level. 

The  mine  is  well  equipped  with  steam  hoist,  air-compressors,  machine 
shop,  and  other  accessories,  but  has  as  yet  no  mill. 

In  recovering  the  old  Lincoln  shaft,  the  settling  of  the  ground  had 
forced  the  shaft  out  of  line,  which  necessitated  the  removal  of  a  large 
amount  of  ground  from  the  hanging-wall  side  of  the  shaft.  To  keep  it 
in  alignment  this  space  was  timbered  in  square  sets,  the  number  of  the 
sets  varying  with  the  distance  from  the  shaft  to  the  solid  ground.  This 
has  not  been  found  to  give  any  trouble. 

In  swelling  ground,  such  as  is  found  in  this  mine  and  many  others  in 
this  county,  experience  has  demonstrated  the  advisability  of  cutting 
large  stations  and  placing  sets  outside  of  the  main  station  sets ;  lagging 
openly — leaving  spaces  8  to  10  inches  between  the  lagging,  which 
preferably,  should  be  light.  These  light  lagging,  under  pressure  from 
the  swelling  ground  or  from  a  squeeze,  will  bend  and  eventually  break 
thus  giving  sufficient  warning  before  material  damage  results  to  the 
main  members  of  the  set.  The  open  spaces  are  useful  in  cutting  out 
and  removing  the  swelling  ground,  and  the  lagging  may  be  removed  if 
necessary,  but  the  main  timbers  will  only  occasionally  require  resetting 

or  renewing.     There  are  24  men  employed. The  Lincoln  Gold  Mine 

Development  Company  of  San  Francisco,  owners.  E.  C.  Voorheis, 
superintendent. 

Mutual  Mine. — On  the  summit  of  the  ridge  between  Sutter  Creek  and 
Amador  City.  A  vertical  shaft  has  been  sunk  on  this  property  to  a 
depth  of  400  feet  (March  1, 1900).     Cross-cuts  are  being  run  to  prospect 


THE   MOTHER    LODE    REGION — AMADOR   COUNTY.  75 

two  veins,  one  of  which  lies  in  the  black  slate  on  the  hanging-wall  side 
of  the  shaft,  and  the  other  in  greenstone  schist  on  the  foot-wall  side. 
The  hanging-wall  vein  has  been  reached  and  good  ore  found  in  a  drift 
on  the  vein.  In  some  surface  workings  very  good  ore  was  taken  from 
the  foot-wall  vein.  The  mine  has  a  substantial  steam  hoist,  and  is 
otherwise  well  equipped  for  prospecting.     There  are  15  men  employed. 

Mutual  Mining  Company  of  San  Francisco,  owners.     S.  R.  Porter 

of  Sutter  Creek,  superintendent. 

Baliol  Mine. — This  is  1  mile  east  of  Sutter  Creek,  and  comprises  a 
number  of  claims  on  patented  agricultural  lands,  and  covers  a  series  of 
veins  in  amphibolite  schist.  An  inclined  shaft  has  been  sunk  to  a  depth 
of  750  feet,  with  levels  at  200,  300,  500,  and  700  feet  and  stations  at  400 
and  600  feet.  In  a  cross-cut  run  easterly  from  the  shaft,  a  distance  of 
380  feet,  four  of  the  veins  have  been  intersected;  No.  1,  the  foot-wall 
vein,  is  cut  at  a  distance  of  110  feet  from  the  shaft,  and  is  about  12 
feet  wide  ;  No.  2,  39  feet  farther  east,  is  from  7  to  17  feet  wide ;  No.  3,  35 
feet  eastward,  is  60  feet  wide ;  and  No.  4,  74  feet  beyond  the  last,  is  6 
feet  wide.  Since  February,  1900,  a  cross-cut  east  from  the  500  station  has 
discovered  higher  grade  rock  than  any  found  in  the  veins  above  men- 
tioned. All  stoping  is  done  by  means  of  machine  drills.  The  diamond 
drill  has  been  used  with  good  results  in  this  property,  bore  holes  driven 
to  the  eastward  having  cut  good-sized  bodies  of  ore  some  distance  from 
the  main  development  of  the  mine.  A  large  amount  of  ore  has  been 
stoped  from  three  large  open  cuts,  all  showing  a  similar  character  of  ore. 
The  large  veins  resemble,  somewhat,  those  of  the  Utica-Stickle  mines  of 
Angels.  The  foot-wall  is  diabase  tuff,  slightly  schistose.  The  hanging- 
wall  is  also  of  this  character,  but  farther  east  are  intrusions  of  granitic 
rock.  A  granular-dike  rock  of  light-gray  color,  much  silicified,  and 
containing  about  2^  per  cent  sulphurets,  constitutes,  together  with  vein- 
like masses  of  quartz,  the  principal  ore-shoots  in  this  mine.  Occasionally 
copper  sulphide  and  arsenical  sulphide  ores  are  found.  The  property  is 
equipped  with  a  40-stamp  mill,  the  stamps  weighing  1100  pounds,  drop- 
ping 5  inches  102  times  a  minute.  No.  35  mesh  punched  tin  screens  are 
used,  the  discharge  being  from  4^  to  5  inches  high.  The  capacity  of  the 
mill  is  4^  tons  per  stamp.  Chrome-steel  shoes  and  cast-iron  dies  are  in 
use;  one  shoe  will  outlast  three  dies,  the  life  of  the  shoe  being  112  days. 
Risdon  vanners  are  used  for  concentration.  There  is  no  canvas  plant. 
The  plates  are  60  inches  by  24  feet,  with  a  l|-inch  drop.  The  apron  plates 
are  on  carriages,  and  may  be  rolled  away  from  the  front  of  the  battery 
when  necessary  to  clean  up.  The  plates  are  dressed  as  often  as  neces- 
sary— usually  twice  in  24  hours.  The  proportion  of  free  gold  is  variable, 
constituting  from  40  to  70  per  cent  of  the  values.  The  sulphurets  are 
shipped  to  Selby's.  The  mill  and  air-compressor  are  run  by  water  power. 
The  hoist  is  operated  by  air,  the  compressor  being  located  at  the  mill. 


76  CALIFORNIA    STATE   MINING   BUREAU. 

It  has  an  automatic  hydraulic  governor,  made  at  the  Knight  foundry  of 
Sutter  Creek.  This  maintains  a  pressure  at  80  to  100  pounds.  The 
compressor  is  driven  by  a  water-wheel  under  452  feet  head.     There  are 

100  men  employed. The  Western  Gold  Mining  Company,  owners. 

W.  H.  Storms  of  Sutter  Creek,  superintendent. 

Potazuha  Mine. — It  is  situated  1^  miles  east  of  Sutter  Creek,  adjoining 
the  Baliol  on  the  west.  The  shaft  has  been  sunk  to  a  depth  of  500  feet 
on  the  vein,  with  a  sump  40  feet,  by  means  of  a  small  steam  hoist. 
Levels  have  been  run  at  100,  200,  and  350  feet;  the  shaft  and  levels  are 
on  the  vein,  which  varies  from  a  few  inches  to  12  feet  in  thickness.  The 
foot-wall  portion  of  the  ledge  has  proven  very  rich.  At  the  Zeila,  Wild- 
man,  and  Baliol  mills  were  made  several  runs  of  the  rock  from  this 
foot-wall  strip,  which  have  produced  about  $15,000,  averaging  about  $25 
per  ton,  some  of  the  ore  running  as  high  as  $100  per  ton.  The  hanging- 
wall  portion  of  the  vein  is  low  grade.  The  mine  is  in  the  hands  of  a 
local  company,  which  has  spent  $40,000  in  its  development.  Heavier 
machinery  will  be  required  to  sink  to  greater  depth.  At  present  the 
mine  is  idle  from  lack  of  funds  to  properly  equip  it,  although  it  is 

expected  to  resume  operations  some  time  this  year. The  Potazuba 

Company  of  Sutter  Creek,  owners.  W.  J.  McGee  of  Sutter  Creek,  sec- 
retary. 

Treadwell  &  Guliana  Mine. — This  is  8  miles  east  of  the  town  of 
Sutter  Creek.  There  are  two  veins  in  the  property,  on  one  of  which,  the 
Treadwell,  there  are  two  tunnels,  one  700  feet,  the  other  300  feet  in 
length;  besides  which  there  are  numerous  superficial  cuts.  The  vein  is 
from  1  foot  to  12  feet  wide,  and  has  produced  some  high-grade  ore.  The 
Guliana  vein  was  discovered  in  the  bed  of  Sutter  Creek,  where  it  is  3 
feet  in  width,  showing  free  gold.  There  is  a  30-foot  shaft  and  a  short 
tunnel  on  this  vein.  The  mine  is  idle.  The  mill  which  was  formerly 
on  the  property  is  dismantled.  The  mill  contained  6  stamps,  and  was 
operated  by  water  under  150-foot  head  with  a  10-inch  pipe-line.  This 
did  not  apparently  afford  sufficient  power  to  run  the  mill,  and  it  was 
consequently  shut  down.  Several  years  later,  it  is  said,  it  was  discov- 
ered that  in  some  manner  a  piece  of  scantling  had  gotten  into  the  pipe- 
line, descended  by  suction  to  the  nozzle,  clogging  it,  and  reducing  the 

power  to  the  extent  described. M.  D.  Nixon  et  al.  of  Sutter  Creek, 

owners. 

Free  American  Mine. — This  is  6  miles  east  of  Sutter  Creek,  on  a 
small  vein  of  high-grade  rock  in  Calaveras  formation.  In  one  place  it 
is  stated  that  the  vein  is  6  feet  wide,  and  that  the  rock  will  run  $25  per 
ton,  and  at  the  bottom  of  the  shaft  the  vein  is  8  feet  wide  in  good  mill- 
ing ore.  The  shaft  has  been  sunk  to  a  depth  of  110  feet  near  Sutter 
Creek,  and  a  drift  extended  out  under  the  creek  along  the  vein,  with  the 


THE    MOTHER   LODE    REGION — AMADOR   COUNTY.  77 

result  that  the  mine  was  flooded,  the  surface  water  probably  coming 
directly  from  the  creek.  The  property  was  provided  with  both  water 
and  steam  hoist,  a  jackhead  pump  and  a  steam  pump,  both  of  which 
were  operated  as  vigorously  as  the  power  would  permit,  in  addition  to 
bailing  with  the  skip  at  the  same  time;  but  this  combination  failing  to 
lower  the  water  in  the  shaft,  operations  had  to  be  abandoned.     A  light 

10-stamp  mill  forms  a  portion  of  the  equipment  of  the  mine. Wilfred 

Dennis  of  Sutter  Creek,  owner. 

South  Spring  Hill  Mine. — This  property  adjoins  the  Keystone  on 
the  south,  and  is  in  many  respects  similar  to  it  geologically.  After  an 
idleness  of  about  seven  years,  operations  were  resumed  in  June  last,  and 
at  this  writing  (June  10th)  the  mill  is  about  ready  to  start.  It  is  said 
that  good  ore  is  being  found  at  the  north  end  of  the  mine. — South 
Spring  Hill  Mining  Company,  owners.  John  R.  Tregloan  of  Amador 
City,  superintendent. 

Soioth  Keystone  Consolidated  Mine. — This  is  half  a  mile  south  of 
Amador  City,  adjoining  the  South  Spring  Hill.  It  is  in  the  prospective 
stage. — J.  A.  Mclntyre  of  Amador  City,  owner. 

Keystone  Mine. — This  is  at  Amador  City,  and  is  one  of  the  most 
extensively  developed  mines  in  the  State.  There  are  probably  not  less 
than  10  miles  of  underground  workings  in  this  famous  old  mine;  but  all 
work  at  present  is  confined  to  points  above  the  1000-foot  level,  although 
the  shaft  is  1575  feet  in  depth.  The  formation  at  the  Keystone  Mine 
consists  of  diabase  tuff,  tufaceous  slates,  and  the  clay  slates  of  the 
Mariposa  beds,  the  latter  lying  west  of  the  principal  veins.  To  the  west 
of  these  clay  slates,  massive  diabase  is  again  found.  The  principal  veins, 
however,  are  those  occurring  in  the  tufaceous  slates.  The  main  vein  occurs 
along  a  fault  plane,  which  has  a  variable  dip  from  35  to  65  degrees  to 
the  eastward  and  extending  more  than  2000  feet  in  a  remarkably  straight 
course.  On  the  hanging-wall  side  of  this  fault  plane  occurs  immense 
masses  of  diabase  material  and  quartz,  which  in  places  is  more  than 
100  feet  in  width.  Considerable  portions  of  this  constitute  payable  ore, 
although  there  are  large  quantities  which  it  will  not  pay  to  mine.  This 
great,  massive  vein  forms  the  hanging-wall  of  a  banded  slaty  vein, 
which  has  produced  a  large  amount  of  pay  rock  south  of  the  main  shaft. 
Between  the  400  and  600  levels  on  this  vein  an  immense  stope  covering 
a  superficial  area  of  20,000  square  feet  has  been  cut,  the  vein  in  places 
being  25  feet  in  width.  There  are  few  timbers  and  but  one  or  two 
pillars  in  this  great  stope,  which  has  been  open  for  years,  which  indi- 
cates how  well  this  ground  stands  without  artificial  support.  This  is 
probably  the  largest  open  stope  on  the  Gold  Belt.  This  was  being  filled 
as  rapidly  as  possible  during  my  visit,  in  order  that  the  large  amount 
of  ore  known  to  lie  in  the  overhanging  (so  called)  wall  may  be  mined 


78  CALIFORNIA   STATE   MINING    BUREAU. 

without  danger.  On  the  hanging-wall  side  of  these  veins  is  a  green- 
stone formation  several  hundred  feet  in  width,  through  which  a  cross- 
cut has  been  run  from  a  neighboring  gulch.  Sections  cut  for  microscopic 
study  (Nos.  10  and  11)  prove  this  rock  to  be  diabase  tuff.  Lying 
between  this  massive  tuff  and  a  broad  zone  of  black  tufaceous  slate  is  a 
dike  of  crystalline,  granular  diabase  of  normal  t5'-pe.  The  tufaceous 
slates  are  from  400  to  600  feet  in  width,  and  constitute  the  zone  of  Assur- 
ing in  which  are  found  the  several  veins  and  ore-shoots  of  the  Keystone 
Mine.  The  veins  all  intersect  the  inclosing  rocks  in  strike  and  dip,  the 
dip  of  the  slates  always  being  steeper  than  that  of  the  veins,  excepting 
where  disturbed  locally.  The  region  of  greatest  disturbance  is  found  in 
the  western  portion  of  this  slate  zone.  The  great  quartz  vein  lying  in 
the  hanging-wall  side  of  this  zone  is  from  1  foot  to  more  than  100  feet 
in  width  when  measured  at  right  angles  to  its  dip.  It  is  made  up  of 
great  lenticular  masses  of  quartz  and  brecciated  quartz  and  diabase, 
having  interior  fissures  or  planes  running  nearly  parallel  with  the 
strike  of  the  vein.  These  are  usually  referred  to  as  walls.  Some  of 
these  masses  are  built  up  by  the  splicing  of  the  lenses.  On  the  800- 
foot  level,  and  a  few  feet  distant  in  the  east  wall  of  this  vein,  is  an 
interesting  though  small  vein  in  a  reef  of  pyritic,  black  tufaceous  slate. 
Through  the  center  of  this  reef  is  found  a  small  irregular  vein  of  quartz, 
with  a  small  gouge  and  with  numerous  flat  branching  seams.  The 
occurrence  of  arsenical  iron  sulphides  is  a  marked  and  persistent 
feature  of  this  little  vein,  but  a  more  interesting  feature  is  the  occur- 
rence of  pockets  of  gold,  ranging  in  value  from  a  few  cents  to  over  a 
hundred  thousand  dollars.  The  latter  was  obtained  between  the  800 
and  900  levels.  Within  the  past  year,  Mr.  W.  A.  Prichard,  the  superin- 
tendent, has  discovered  a  number  of  good-sized  gold  pockets  in  this 
vein.  On  the  800-foot  level  a  dike  of  diabase  intervenes  between  the 
great  massive  vein  and  the  pocket  vein  above  described,  while  on  the  900- 
foot  level,  about  200  feet  farther  north,  the  diabase  and  reef  of  pyritic 
slate  are  passed  through  before  the  great  vein  is  encountered.  Arsenical 
sulphide  was  also  discovered  on  the  900-foot  level,  in  this  vicinity. 
Although  no  pockets  have  been  found  on  the  900-foot  level,  or  below  it, 
the  indications  are  that  the  pocket  vein  is  older  than  the  great  vein 
cutting  across  it,  and  that  the  pocket  shoot  may  be  found  from  the  900- 
foot  level  downward  in  the  foot-wall  of  the  great  vein.  In  the  large 
vein  are  found  the  widest  stopes  in  the  mine.  West  of  this  are  two 
veins,  separated  from  each  other  and  the  great  vein  by  varying  widths 
of  tufaceous  slates.  These  veins  were  also  extensively  worked  in  former 
years. 

A  careful  and  detailed  study  of  the  Keystone  Mine  would  undoubtedly 
furnish  material  for  a  book  much  larger  than  the  volume  in  which  this 
description  is  found.     There  are  90  men  employed  in  the  mine  and  mill. 


THE    MOTHER    LODE    REGION-^AMADOR    COUNTY, 


(9 


Keystone   Consolidated   Mining   Company  of  San    Francisco,  owners. 
W.  A.  Prichard  of  Amador  City,  superintendent. 

Keystone  Mill. — The  mill  consists  of  40  stamps,  and  two  Griffin  mills. 
The  latter  were  formerly  used  in  crushing  the  fine  material  from  the 
mine,  but  are  at  present  not  in  use.  The  mill  is  run  by  water  power, 
and  the  hoist  by  steam.  The  mill  is  under  the  direction  of  C.  E.  Bunker. 
The  stamps  when  new  weigh  725  pounds.  Prior  to  March  10, 1890,  they 
were  dropped  90  times  a  minute.  A  Pelton  wheel  was  put  in  the  mill 
at  this  time  to  run  the  concentrators  independently,  and  the  stamps 
were  speeded  to  about  100  drops  a  minute,  the  height  of  the  drop  being 
from  7  to  7^  inches,  and  the  discharge  7^  inches  high.     Nos,  6  and  7 

CoRRUQATtD      PLATfc- 

Chuck  Block  of-  Keystone  Mi lu, 

Ar-lo 

Device:  for    re^uiafm^    >^e.i6i-yi-  oT 

discl-jar'd.e. 


Fig.  27. 

angle-slot  steel  screens  are  used.  The  chuck-blocks  are  arranged  so  as 
to  drop  half  an  inch  at  a  time.  A  variety  of  shoes  and  dies  have  been 
tried  here,  including  cast-iron,  manganese,  chrome,  and  hammered  steel. 
The  capacity  of  the  mill  per  stamp  is  24  to  3  tons  per  day,  varying 
somewhat  with  the  character  of  the  ore.  This  low  capacity  is  probably 
attributable  to  the  light-weight  stamps.  The  inside  plate  is  curved, 
and  6  inches  in  width.  The  apron  plates  are  52  inches  wide  and  4  feet 
long,  having  a  grade  of  1^  inches  in  12.  Below  this  the  plates  are  nar- 
rowed to  48  inches  for  a  length  of  10  feet,  below  which  they  are  further 
narrowed  to  30  inches  and  24  inches  long,  with  a  trap  at  the  bottom. 

Since  February  1,  1900,  numerous  changes  have  been  made  in  this 
mill.     On  an  experimental  battery,  the  chuck-block  has  been  changed 


80  CALIFOKNIA    STATE   MINING    BUREAU. 

SO  as  to  reduce  the  width  of  the  mortar  2  inches,  by  placing  the  screen 
flush  with  the  main  frame.  The  stamps  have  been  speeded  to  100  drops 
a  minute;  the  discharge  has  been  lowered,  and  closer  attention  is  being 
given  to  outside  amalgamation.  The  apron  plate  has  been  widened  to 
60  inches  for  a  length  of  16  feet,  and  the  grade  of  these  plates  has  been 
reduced  to  1|  inches  per  foot.  No  water  is  added  outside  the  batteries, 
as  in  all  the  others,  and  the  inside-battery  water  has  been  reduced  to 
the  lowest  possible  amount.  The  lowering  of  the  discharge  would  prob- 
ably have  increased  the  capacity  of  the  mill,  but  the  decrease  in  the 
amount  of  battery  water  has  a  tendency  to  retard  discharge.  The 
capacity  of  this  battery  is  about  the  same  as  that  of  the  other  batteries, 
but  as  a  result  of  these  changes,  the  tailings  have  shown  a  marked 
decrease  in  value,  and  it  is  the  intention  to  adapt  the  entire  mill  to  these 
changes.  A  new  chuck-block  with  corrugated  copper  plate  (see  Fig.  27) 
has  been  introduced  in  this  mill. 

Bunker  Hill  Mine. — It  is  1^  miles  north  of  Amador  City.  This  prop- 
erty is  a  consolidation  of  the  Bunker  Hill  and  May  Flower.  On  it  is  a 
shaft  in  the  May  Flower  350  feet  in  depth.  The  old  shaft  of  the 
Bunker  Hill  was  sunk  to  a  depth  of  800  feet;  it  had  been  closed  for  a 
number  of  years  when  it  was  re-opened  in  the  latter  part  of  1899.  The 
upper  portion  of  the  shaft  was  badly  caved,  which  required  a  great  deal 
of  work  to  recover.  A  cross-cut  tunnel  was  driven  some  years  since 
near  the  base  of  the  hill  to  connect  with  the  old  May  Flower  shaft  at  a 
station,  and  a  branch  driven  beyond  in  the  direction  of  the  Bunker 
Hill.  This  latter  has  been  continued  to  the  Bunker  Hill  vein,  it  being 
the  intention  to  drain  the  mine  of  surface  water  through  this  tunnel. 
There  is  also  a  shaft  400  feet  deep  on  the  south  end  of  the  property. 
The  hanging-wall  of  the  vein  is  a  fine-grained  grayish  rock  (No.  16), 
in  places  carrying  considerable  finely  disseminated  iron  sulphide;  this 
rock  is  diabase  tuff,  greatly  altered.  The  slates  found  in  the  foot-wall 
are  the  result  of  alteration  of  tufaceous  diabase,  and  bear  the  character- 
istic pitted  marks  which  distinguish  this  class  of  slates  in  Amador. 

In  its  early  history,  the  Bunker  Hill  is  credited  with  a  production  of 
about  $1,000,000  down  to  the  700-foot  level.  The  shoots  have  a  southerly 
trend.     The  mine  is  equipped  with  a  substantial  steam  hoist,  but  as  yet 

has  no  mill.     20  men  are  employed. The  Bunker  Hill  Consolidated 

Mining  Company,  owners.    C.  R.  Downs  of  Sutter  Creek,  superintendent. 

Fremont  Mine. — This  property,  1^  miles  north  of  Amador  City,  com- 
prises the  Fremont,  Gover,  and  Loyal  Lode,  4200  feet  on  the  lode.  The 
principal  work  on  this  property  is  on  the  Gover  Mine,  the  main  shaft 
of  which  is  down  1500  feet  on  an  incline,  being  1050  feet  vertical.  There 
are  ten  levels,  and  in  the  lower  levels  of  the  mine  there  are  developed 
large  masses  of  low-grade  quartz.  In  the  early  part  of  the  present  year, 
a  new  shaft  was  started  on  the  Fremont  claim.     This  is  an  inclined 


THE    MOTHER    LODE    REGION — AMADOR   COUNTY.  81 

shaft,  sunk  at  an  angle  of  51  degrees  below  the  horizon.  It  is  started 
in  the  hanging-wall  of  the  vein,  which  it  is  calculated  to  intersect  in 
depth.  The  close  proximity  of  the  old  flooded  works  of  the  Gover  will 
probably  render  the  sinking  of  this  new  shaft  a  difficult  if  not  dangerous 
operation;  at  least  such  has  been  the  experience  of  others  who  have 

attempted  to  sink  new  shafts  in  the  vicinity  of  old  flooded  workings. 

Gover  Consolidated  Gold  Mining  Company,  10  Market  street,  San  Fran- 
cisco, owners.     C.  E.  Purington  of  Amador  City,  superintendent. 

Phoinix  Reduction  Works  (Chlorination). — This  is  at  Dry  town,  and 
consists  of  a  single  reverberatory  furnace,  with  all  the  essential  vats, 
etc.,  for  a  complete  plant  of  the  Plattner  type.  (No  barrel  chlorination 
is  practiced  in  this  State.)  The  Dry  town  plant  has  a  capacity  of  3  tons 
daily,  and  treats  custom  ores  only.  There  are  5  men  employed.  E.  S. 
Barney  of  Drytown,  owner  and  superintendent. 

In  the  chlorination  process  as  practiced  in  Amador  County,  the 
auriferous  sulphides  which  are  derived  from  the  ores  by  the  various 
methods  of  concentration,  are  charged  in  reverberatory  furnaces  usually 
containing  about  10  per  cent  moisture.  The  charge  is  moved  forward  on 
the  hearth  every  eight  hours,  and  a  new  charge  introduced.  These 
furnaces  are  from  60  to  65  feet  in  length  and  from  11  to  14  feet  wide. 
Pine  wood  is  used  for  fuel,  the  quantity  required  per  ton  of  sulphides 
being  one  fourth  to  one  third  of  a  cord.  The  charge  of  ore  ranges  from 
2000  to  2500  pounds.  Three  charges  are  introduced  every  twenty-four 
hours.  A  '"dead  roast"  is  absolutely  essential  to  a  complete  and  suc- 
cessful extraction  of  the  gold.  Dampers  are  provided  in  the  stacks, 
which  are  manipulated  with  the  greatest  care. 

When  the  sulphides  take  fire,  and  following  the  volatilization  of  the 
arsenic,  should  any  be  present,  but  while  sulphur  still  remains,  salt  is 
added.  After  the  pulp  has  been  withdrawn,  it  is  allowed  to  cool  and  is 
dampened,  the  proper  amount  of  moisture  being  determined  by  com- 
pressing a  quantity  in  the  hand.  If  it  fails  to  crumble,  it  contains  too 
much  moisture;  if  it  crumbles  rapidly,  the  amount  of  moisture  is 
insufficient;  but  when  the  compressed  ball  slowly  disintegrates,  it  is 
considered  to  have  the  proper  amount  of  moisture.  The  pulp  is  charged 
in  vats  by  being  shaken  over  screens,  the  charge  being  from  4  to  6  tons. 

Chlorine  gas  is  generated  in  lead-lined  vessels,  the  following  materials 
being  employed:  salt,  50  to  60  pounds;  manganese  dioxide,  30  to  40 
pounds;  sulphuric  acid,  added  as  long  as  gas  is  generated.  When  the 
vats  have  been  charged  with  pulp,  the  gas  is  turned  in,  passing  ,upward 
through  the  false  bottom  of  the  vat,  penetrating  the  charge,  and  event- 
ually reaching  the  surface.  Tanks  are  gassed  until  it  shows  near  the 
surface  of  the  charge,  which  usually  occurs  in  from  three  to  five  hours, 
when  the  cover  is  luted  on.  The  gas  is  shut  off  when  it  appears  on  the 
6 — MB 


82  CALIFORNIA    STATE    MINING    BUREAU. 

surface.  This  period  is  determined  by  holding  a  bottle  of  anamonia  near 
a  small  vent  in  the  cover.  Upon  the  appearance  of  the  chlorine  gas 
through  this  vent,  a  dense  cloud  of  chloride  of  ammonium  at  once  forms- 
Water  is  introduced  through  a  hole  in  the  cover,  falling  on  a  burlap 
sack.  It  is  a  common  practice  to  allow  the  water  to  stand  from  one  to 
two  hours,  when  it  is  turned  into  the  precipitating  tank.  The  water  is 
permitted  to  run  until  the  iron  sulphate  solution  fails  to  show  the 
presence  of  gold,  samples  being  taken  from  the  vat.  If  the  assay  of 
samples  shows  that  high  values  remain  in  the  pulp,  it  must  be  removed 
from  the  vats  and  "regassed."  The  leaching  vats  are  provided  with  a 
double  floor;  these  are  made  with  slats  1^  inches  in  width  placed  18 
inches  apart.  Upon  these  and  at  right  angles  to  the  first  are  laid  1-inch 
boards  4  inches  wide,  covering  the  bottom;  these  are  2  inches  apart. 
Upon  this  floor  is  placed  a  quantity  of  quartz  gravel  (clean  creek 
gravel  being  preferred),  usually  laid  in  courses,  to  a  depth  of  about  6 
inches.  Upon  this  filter  are  laid  the  shoveling  boards,  4  inches  wide 
and  1  inch  in  thickness,  they  being  separated  by  a  space  of  1  inch. 
These  spaces  are  filled  in  with  fine  gravel  which  will  pass  a  No.  12 
screen.  A  solution  of  iron  sulphate  is  employed  to  precipitate  the  gold 
from  the  chloride  solution.  The  precipitate  is  washed  and  smelted  with 
borax. 

Centennial  Mine. — This  property  is  1^  miles  northeast  of  Drytown. 
An  inclined  shaft  has  been  sunk  565  feet,  and  sinking  was  in  progress 
in  April  last.  This  shaft,  started  on  the  vein,  passes  into  the  foot- wall, 
and  cross-cuts  are  run  to  the  vein  at  the  150,  250,  and  350  levels.  On 
the  first  the  vein  was  found  from  8  to  8  feet  wide;  on  the  second,  18 
feet;  and  on  the  third,  about  2  feet.  The  shaft  will  be  continued  to  a 
depth  of  1000  feet.     The  formation  is  greenstone  schist  (after  diorite). 

Centennial  Mining   Company,  owners.     L.  A.  Gross  of  Drytown, 

superintendent. 

The  formation  from  the  neighborhood  of  Drytown  to  Plymouth  is 
largely  amphibolite  schist  and  diorite,  tufaceous  slates,  and  Mariposa 
clay  slates.  Many  veins  of  quartz  occur,  both  large  and  small,  and 
also  zones  of  amphibolite  schist  with  quartz.  There  are  many  prospect 
holes  of  various  depths  throughout  the  region,  but  with  the  exception  of 
those  here  mentioned,  no  operating  mines. 

Plymouth  Consolidated  Mine. — This  property  is  at  Plymouth,  and  has 
been  idle  for  many  years,  but  within  the  past  year  the  old  dumps  have 
been  worked  with  profit  in  Huntington  mills.  These  dumps  were 
estimated  to  contain  over  250,000  tons  of  rock.  The  reduction  plant 
consists  of  four  5-foot  Huntington  mills  with  hydraulic  sizers,  Wilfley 
and  Woodbury  concentrators,  and  canvas  plant.  Power  is  furnished  by 
water  from  the  Hayward  ditch  under  a  head  of  572  feet.     The  dumps 


THE    M0THP:R    I-ODE    region — AMADOR   COUNTY,  83 

were  moved  at  very  low  cost  by  cutting  in  at  their  base*  and  running  an 
open  cut  directly  into  the  end  of  the  pile  of  rock.  When  a  face  of  suf- 
ficient size  had  been  exposed,  a  movable  chute  was  placed  against  the 
face,  by  means  of  which  all  the  rock  above  the  level  of  the  chute  was 
easily  delivered  to  cars  beneath  the  chute.  The  rock  was  trammed  to 
the  mill,  hoisted  in  the  car  by  means  of  a  hydraulic  elevator,  dumped 
onto  the  grizzlies,  from  which  it  passed  to  the  rockbreakers,  falling 
into  a  bin.  From  the  bin,  the  rock  was  delivered  to  automatic  feeders, 
thence  to  the  mills. 

Diagonal  slot  screens  from  12  to  20  mesh  are  in  use.  From  the  mill 
the  pulp  flows  to  the  sizers,  from  which  the  coarse  material  goes  to  the 
concentrating  tables  and  the  slimes  to  the  canvas  plant.  The  principal 
source  of  value  in  the  dumps  is  in  the  sulphurets,  which  average  about 
1|  per  cent.  The  free  gold  is  caught  with  the  concentrates,  which  are 
shipped  to  Selby's.  The  following  statement  is  made  by  the  manage- 
ment relative  to  the  cost  of  working: 

Thirty  Days'  Milling,  3750  Tons. 

Cost  of  delivering  rock  to  mill |375  00 

Milling,  including  canvas  plant 510  00 

Water - 240  00 

General  expense 110  00 

Total _..     $1,235  00 

Total  cost  per  ton 32 

The    New   Western    Mining    and    Reduction    Company,   owners. 

T.  C.  Woodworth  of  Plymouth,  superintendent. 

Pocahontas  Mine. — This  property  is  1^  miles  east  of  Drytown,  and 
includes  the  Pocahontas,  Edson,  and  California,  the  owners  holding  a 
bond  on  the  Maryland  claim  adjacent.  A  vertical  shaft  has  been  sunk 
on  the  Pocahontas  to  the  depth  of  620  feet,  with  six  levels.  The  forma- 
tion is  practically  a  black  tufaceous,  pitted  slate,  to  the  west  of  which 
lie  the  Mariposa  clay  slates.  Over  1000  feet  of  cross-cuts  have  been  run, 
extending  from  the  Mariposa  slates  on  the  west  to  massive  diabase  on 
the  east.     The  property  is  provided  with  a  good  steam  hoist,  and  a 

10-stamp  mill  run  by  water  power.     There  are  6  men  employed. The 

Pocahontas  Improvement  Company  of  Drytown,  owners.  Allen  Mc  Wayne 
of  Drytown,  superintendent. 

Pioneer  Mine. — It  is  1  mile  south  of  Plymouth,  and  comprises  a  mile 
on  the  lode,  which  consists  of  two  veins;  the  east  or  hanging- wall  vein 
of  massive  quartz,  and  the  west  vein  banded  structure.  The  latter  is 
usually  the  better  vein.  These  veins  occur  in  the  black  tufaceous  slates 
An  inclined  shaft  has  been  sunk  500  feet  on  the  foot-wall  vein,  and  in 
the  several  levels  three  shoots  of  ore  have  been  developed.  In  some 
respects  these  shoots  of  ore  are  similar  to  those  of  the  Central  Eureka  at 
Sutter  Creek.  The  lower  workings  of  the  mine,  however,  are  in  low- 
grade  ore,  and  appear  to  have  reached  a  zone  of  little  or  no  pay  rock. 


84  CALIFORNIA    STATE    MINING    BUREAU. 

which  seems  to  be  a  peculiar  characteristic  of  many  of  the  most  impor- 
tant mines  of  Amador  County.  Geologically,  the  outlook  for  the  future 
of  the  Pioneer  Mine  may  be  considered  as  encouraging,  as  there  is  no 
reason  to  anticipate  that  it  may  not  at  greater  depth  repeat  the  experi- 
ence of  the  Kennedy  and  Argonaut,  Central  Eureka,  and  other  mines  in 
this  county. Dr.  Thomas  Boyson,  owner. 

Philadelphia  Mine. — It  is  4  miles  north  of  Plymouth,  near  the  Bay 
State.  Several  years  ago  this  mine  was  opened  by  means  of  a  large  cut 
and  drift,  when  operations  were  suspended,  and  the  mine  remained  idle 
until  the  spring  of  1900,  when  a  new  double-compartment  shaft  was 
started  1000  feet  south  of  the  old  open  cut.  This  shaft  had  reached  a 
depth  of  80  feet  early  in  June.  Its  hanging- wall  is  diabase;  the  foot- 
wall  is  black  slate.  The  vein  formation  is  20  feet  in  width.  There  are 
kidneys  of  good  rock  on  the  foot-wall  side.     The  shaft  is  equipped  with 

a  water-power  hoist,  capable  of  going  1000  feet. J.  J.  Crawford,  Claus 

Spreckels  Building,  San  Francisco,  owner.  Leased  to  -J.  R.  Roaf  et  al. 
of  Toronto,  Canada. 

Ivanhoe  Mine. — It  is  H  miles  northeast  of  Plymouth.  The  mine 
occurs  in  a  zone  of  amphibolite  schist,  and  is  developed  by  a  ver- 
tical shaft  130  feet  deep,  and  also  by  an  inclined  shaft  120  feet. 
It  has  a  20-stamp  mill  and  a  steam  hoist.     It  has  been  described  in 

former  reports,  and  was  closed  down  in  the  spring  of  1900. Under 

bond  to  the  Ivanhoe  Gold  Mining  Company  of  Salt  Lake.  E.  Brent  of 
Sutter  Creek,  superintendent. 

Shenandoah  Mine. — It  is  1^  miles  northeasterly  from  Plymouth. 
This  interesting  vein  adjoins  the  Red  Cloud,  described  in  former  reports, 
on  the  south.  The  formation  is  diorite,  which,  near  the  vein,  is  altered 
to  amphibolite  schist.  The  shaft,  early  in  May,  had  reached  a  depth  of 
375  feet,  partly  on  the  vein,  but  the  lower  portion  in  the  foot-wall. 
Drifts  were  run  at  the  200  and  375  levels,  the  latter  from  a  cross- 
cut. There  are  two  veins  in  this  fissure,  one  a  massive  vein  of  quartz, 
the  other  a  banded  or  ribbon  vein.  On  the  south  side  of  the  shaft  the 
banded  vein  lies  on  the  hanging-wall  side  of  the  fissure,  but  on  the  north 
side  it  is  found  on  the  foot-wall  side,  being  separated  from  the  massive 
vein  by  a  small  gouge.  The  massive  vein  appears  to  be  the  older,  it 
having  been  broken  and  crushed  by  the  movement  of  the  rocks.  The 
banded  portion  of  the  vein,  however,  is  quite  regular,  and  shows  no 
structural  indication  of  disturbance.  In  addition  to  gold,  there  are 
found  iron,  lead,  and  copper  sulphides.  The  shaft  has  been  sunk 
between  two  shoots  of  ore,  which  have  a  southerly  trend.  The  mine  is 
equipped  with  a  steam   hoist,  but  has  no  mill.     There  are   12    men 

employed. Shenandoah   Mining   Company  of   Sacramento,  owners. 

S.  K.  Thornton  of  Plymouth,  superintendent. 


THE    MOTHER    LODE    REGION — AMADOR   COUNTY.  85 

Red  Cloud  Mine. — It  is  14  miles  northeast  of  Plymouth,  adjoining  the 
Shenandoah  on  the  north.  It  has  geological  characteristics  similar  to 
those  of  the  Shenandoah.  It  is  idle.  The  shaft  has  been  sunk  to  a 
depth  of  365  feet,  the  upper  portion  of  which  was  caved  at  the  time  of 
my  visit.  The  surface  croppings  are  exposed  in  cuts,  and  show  two 
veins  striking  N.  13°  W.  and  dipping  65  degrees  to  the  east.  The  shaft 
appears  to  have  been  sunk  at  a  point  where  a  fault  has  displaced  the 
vein,  giving  the  appearance  of  two  veins,  whereas  there  is  really  but 
one. The  Red  Cloud  Mining  Company  of  Stockton,  owners. 

Gowanus  Mine. — It  is  2  miles  northeasterly  from  Plymouth.  In  this 
property  there  are  several  large  lens-like  masses  of  quartz  striking 
through  a  much  foliated  amphibolite  schist.  These  lenses  have  a  width 
of  from  1  to  8  feet,  and  occur  across  a  zone  of  150  feet  or  more  in 
width.  They  appear  to  converge  northward.  The  ore  is  granular,  and 
of  a  dark  blue  color  resembling  some  quartzite.  It  is  said  to  mill  $8 
per  ton.  A  three-compartment  shaft  (vertical)  was  being  sunk  during 
the  spring  of  1900,  which  was  calculated  to  reach  the  vein  at  a  depth  of 
200  feet.  At  this  mine  was  found  an  unusual  arrangement  of  a  hoist- 
ing plant.  The  hoist,  which  is  run  by  steam,  is  set  opposite  the 
end  of  the  shaft  instead  of  at  the  side.  This  was  done  with  a  view,  it 
was  explained,  of  leaving  the  ground  for  a  permanent  hoisting  plant 
unobstructed,  and  of  permitting  the  temporary  plant  to  be  operated 
until  the  new  hoist  could  be  placed  in   position.     There  are   8  men 

employed. Gowanus    Mining    Company,    owners.      Mr.   Rogers    of 

Plymouth,  superintendent. 

Bay  State  Mine. — It  is  4  miles  north  of  Plymouth.  There  are  several 
veins  in  this  property.  That  known  as  the  Bay  State  vein  was  formerly 
worked  by  the  Ba}^  State  Company  to  a  depth  of  830  feet;  it  was  stoped 
from  the  400  to  the  600  level.  At  the  750  level  a  cross-cut  was  run 
east  to  the  vein  and  two  shoots  of  ore  developed,  one  dipping  north, 
the  other  south.  The  north  shoot  is  a  banded  vein,  the  south  more 
massive  and  mixed  with  slaty  material.  The  sulphides  found  in  the 
south  shoot  were  high-grade  in  gold.  At  460  feet  west,  on  the  750-foot 
level,  a  west  vein  was  discovered  in  the  cross-cut,  which  is  called  the 
Kretcher  vein.  This  vein  was  observed  at  a  point  346  feet  west  of  the 
shaft  on  the  300-foot  level.  The  Kretcher  vein  has  been  developed  for 
a  distance  of  about  300  feet,  and  consists  of  banded  quartz  of  good 
grade.  At  the  time  of  my  visit  some  improvements  were  being  made 
in  the  shaft,  but  the  mine  was  not  in  full  blast.  The  shaft  will  be  sunk 
an  additional  300  feet.  The  mine  is  equipped  with  a  good  hoist,  and 
has  a  10-stamp  mill  and  an  8-drill  air-compressor,  all  run  by  water. 
The  pumping  is  done  by  air.  The  mill  has  a  capacity  of  40  to  50  tons 
daily.  A  24-mesh  punched  tin  screen  is  used.  The  pulp  passes  directly 
from  the  battery  to  the  vanners,  of  which  there  are  four.     The  tailings 


86  CALIFORNIA    STATE    MINING    BUREAU. 

are  stated  to  contain  but  21   cents  per  ton,  chiefly  in  free  gold.     The 
sulphides  are  shipped  to  the  Drytown  chlorination  works.     There  are 

12    men    employed. The   Globe    Mining    and    Milling   Company  of 

Stockton,  owners.     .J.  L.  Bryson  of  Plymouth,  superintendent. 

Rhetta  Mine. — This  mine  is  about  4  miles  north  of  Plymouth,  adjoin- 
ing the  Bay  State  on  the  south.  It  is  developed  by  means  of  a  cross-cut 
tunnel  about  600  feet  in  length.  There  are  two  veins  on  the  property. 
One  occurs  at  the  contact  of  a  diabase  foot  and  a  black  slate  hanging;  the 
other  branches  out  from  this  contact  vein,  striking  northward  in  the 
hanging-wall  slates.  Both  of  these  veins  have  been  explored  with 
satisfactory  results,  the  ore  being  hauled  to  the  Bay  State  mill  at  a  cost 
of  30  cents  per  ten.  A  large  amount  of  water  is  encountered,  but  this 
causes  little  trouble,  as  it  passes  out  through  an  adit  tunnel.  From  the 
Rhetta  vein  southward  in  the  direction  of  Plymouth,  a  line  of  springs 
marks  the  occurrence  of  fissures  at  or  near  the  contact  of  the  slates  with 
the  greenstone,  and  although  this  section  affords  a  good  field  for  pros- 
pecting, very  little  has  been  done  toward  exploring.     There  are  8  men 

employed. Rhetta    Gold    Mining    Company   of    Stockton,    owners. 

J.  L.  Bryson  of  Plymouth,  superintendent. 

Talc  Mines. — About  6  miles  west  of  Sutter  Creek  is  an  interesting 
occurrence  of  gold  in  foliated  talc  schist,  which  appears  to  be  a  structural 
alteration  of  serpentine.  On  the  Tonzi  and  Waechter  ranches  there  are 
several  zones  of  this  talcose  rock,  in  which  the  gold  occurs  in  extremely 
thin  plates  in  the  foils  of  the  rocks,  much  of  which  is  thin  as  the  finest 
gold  leaf;  while  presenting  the  appearance  of  richness,  gold  of  this 
character  is  very  deceptive.  On  the  Tonzi  ranch,  Mr.  Tonzi  has  erected 
an  ingenious  device  for  crushing  this  ore,  and  claims  to  have  taken  out 
considerable  gold  at  various  times  from  the  best  selected  gold-bearing 
material  found  on  his  place.  That  this  gold-bearing  talc  can  be  profit- 
ably worked,  is  extremely  doubtful;  it  is  possible  that  if  a  zone  of 
sufficient  size,  carrying  $5  or  more  per  ton  in  gold  of  the  character 
described,  could  be  found,  it  might  be  profitably  treated  by  some  modi- 
fications of  the  cyanide  process. 

Azula  Mine. — This  is  3i  miles  northeast  of  lone.  It  is  a  pocket  mine 
in  diabase,  and  has  been  worked  with  considerable  success  by  its  owners. 
Mining  here  is  carried  on  in  rather  primitive  fashion,  but  evidently 
with  satisfactory  results.  The  vein  is  from  16  to  18  inches  in  width, 
the  small  stringers  going  into  the  main  fissure  from  the  hanging- wall. 
Three  men  employed. Adams,  Burris  &  Smith  of  lone,  owners. 

Nugget  Mine. — This  property  is  near  the  Azula,  and  is  similar  to  it. 
It  has  a  small  steam  hoist,  and  a  5-stamp  mill  has  been  constructed 

since  my  visit  to  the  property;  it  was  idle  at  that  time. -Dr.  Adams 

et  al.  of  lone,  owners. 


THE    MOTHER    LODE    REGION — AMADOR    COUNTY.  87 

Queen  Mine. — This  is  in  the  same  group  with  the  Azula  and  Nugget, 

and  is  geologically  similar  to  the  others.     It  has  a  small  steam  hoist. 

Newman,  Bagley  &  Frates  of  lone,  owners. 

Ranlett  Copper  Mine. — It  is  located  3  miles  northeast  of  lone.  The 
ore-bodies  occur  in  the  greenstone  schists  in  which  are  found  many  of 
the  copper  mines  in  this  State.  The  ore  is  that  most  common  to  copper 
mines  in  the  West,  and  is  amenable  to  treatment  by  various  smelting 
methods.  The  development  of  the  mine,  while  not  extensive  as  com- 
pared with  the  great  gold  mines  of  the  State,  is  sufficienth''  so  to  show 
that  it  is  a  mine  of  considerable  possibilities.  An  examination  of  the 
mine  and  maps,  together  with  the  statement  made  by  Colonel  Ranlett, 
indicates  about  30,000  tons  of  ore  in  sight,  including  that  now  on  the 
dumps.  The  ore  may  be  divided  into  two  classes:  a  vein  of  solid,  mass- 
ive, yellow  sulphide  copper  ore,  distinctly  separated  from  the  adjoining 
rock,  and  in  the  foot-wall  a  zone  of  variable  width,  from  4  or  5  feet  to 
15  feet  or  more,  in  which  occurs  a  large  amount  of  iron  sulphide,  with 
a  small  percentage  of  copper  sulphide.  In  this  zone  there  are  segregated 
bands  of  ore  above  the  average  of  the  zone  in  value,  and  which  by 
rough  sorting  may  afford  a  valuable  product,  though,  of  course,  not  so 
high  a  grade  as  that  found  in  the  massive  vein.  This  ore  contains 
considerable  silica,  and  may  become  valuable  as  a  flux  in  treating  the 
more  massive  ore.  The  levels  already  opened  are  practically  without 
cross-cuts;  at  least,  such  as  have  been  made  are  not  in  ore,  and  others 
should  be  made  in  the  foot-wall  for  the  purpose  of  determining  more 
fully  the  extent  and  value  of  the  low-grade  zone.  Manila  ropes  are  in 
use  in  this  mine,  steel  ropes  not  having  given  satisfaction  in  former 
years;  but  I  believe  that  as  so  many  years  have  elapsed  since  steel 
ropes  were  employed  here,  it  would  be  found  that  the  modern  steel  rope 
would  prove  superior  to  the  large,  cumbersome  Manila  ropes  now  in 
use,  even  in  the  present  old  crooked  shaft.  I  am  positive  that  such 
would  be  the  case  in  the  proposed  new  shaft,  which  would  be  sunk  at  a 
uniform  angle.  A  water-jacket  smelter  of  100  tons  capacity  daily  was 
built  at  this  mine  during  May  and  June,  1900.  Not  yet  blown  in,  June 
10,  1900. H.  G.  Ranlett  of  Ranlett,  superintendent. 


88  CALIFORNIA   STATE    MINING   BUREAU. 


EL  DORADO  COUNTY. 


This  county,  which  in  past  years  has  produced  a  very  large  amount 
of  gold,  is  at  present  passing  through  a  temporary  period  of  inactivity, 
due  partly  to  scarcity  of  water  and  to  other  causes  not  wholly  apparent. 
There  have  been  in  the  past  in  this  county,  and  there  are  still,  mines  of 
undoubted  merit,  a  statement  abundantly  proven  by  its  history,  and 
that  the  mines  of  El  Dorado  are  exhausted  cannot  be  entertained.  Some 
large  and  extensively  equipped  enterprises  have  come  into  prominence 
and  have  been  shut  down  since  our  last  report,  but  the  fact  that  there  are 
those  who  have  been  led  into  unprofitable  investment  by  reason  of  the 
exercise  of  too  little  caution  should  not,  and  probably  Avill  not,  deter 
others  from  engaging  in  the  legitimate  pursuit  of  mining  enterprises  in 
this  county  on  more  conservative  lines.  No  mining  county  in  California, 
and  no  mining  region  on  earth,  is  wholly  free  from  these  monuments  of 
men's  folly.  It  is  a  fact  that  in  no  county  in  California  has  mining  _ 
been  carried  on  at  less  expense  than  in  some  of  the  mines  of  El  Dorado, 
and  it  still  offers  abundant  legitimate  and  promising  opportunities  to 
those  with  both  the  capital  and  experience  to  handle  large  low-grade 
mines. 

In  passing  northward  from  Amador  County  into  El  Dorado,  the  Cen- 
tral Gold  Belt,  or  so-called  Mother  Lode,  appears  to  split  up.  The  geo- 
logical conditions  for  adistance  of  five  miles  in  El  Dorado  County  are 
not  wholly  dissimilar  from  those  of  Amador,  consisting  essentially  of 
massive  outcrops  of  white  quartz  at  or  near  the  contact  of  slaty  rocks  and 
massive  greenstones.  These  heavy  outcrops  of  quartz  are  rarely  gold- 
bearing  in  amount  sufficient  to  constitute  payable  rock,  and  they  are 
frequently  accompanied,  as  elsewhere  along  the  Gold  Belt,  by  veins 
having  a  slaty  structure,  in  which  the  gold  contents  are  sufficiently  high, 
in  some  cases  at  least,  to  afi'ord  profit. 

When  the  neighborhood  of  the  German  Mine  is  reached,  5  miles  north 
of  the  Cosumnes  River,  we  find  a  new  and  strange  intrusive  rock — one 
with  which  we  are  not  familiar  in  the  region  farther  southward.  A 
study  of  this  region  shows  that  in  proceeding  northward  some  of  these 
rocks  are  of  granitic  type,  ranging  through  grano-diorite  and  diorite  to 
quartz-porphyry,  and  other  porphyritic  rocks.  As  we  go  farther 
northward,  the  rocks  of  this  character  increase  in  area,  until  in  the 
neighborhood  of  Placerville  they  largely  dominate  all  other  kinds, 
although  the  rocks  with  which  we  are  familiar  farther  southward  (the 
greenstones)  may  still  be  found.     On  a  prominent  hill  just  north  of  the 


THE    MOTHER    LODE    REGION — EL   DORADO   COUNTY.  89 

Church  Mine  are  large  masses  of  rock  of  granitic  type,  of  which  a  care- 
ful investigation  was  made.  The  granitic  outcrop  was  found  to  be  half 
a  mile  in  width,  striking  with  the  general  trend  of  the  country  in  a 
northeasterly  direction.  On  the  eastward,  large  masses  of  diabase  and 
amphibolite  schist  are  found.  A  number  of  rock  specimens  were 
collected  from  various  portions  of  this  mass,  and  slides  were  prepared 
and  studied  by  Mr.  H.  W.  Fairbanks  of  Berkeley,  whose  report  accom- 
panies this  bulletin.  This  investigation  shows  that  specimens  selected 
at  any  particular  portion  of  the  mass,  and  assumed  to  represent  the 
entire  intrusion,  would  be  very  misleading,  for,  in  the  several  slides 
made  from  specimens  taken  from  difierent  portions  of  the  hill,  we  find 
rocks  of  a  decided  acid  character,  and  also  those  of  basic  kind,  with 
many  intermediate  phases.  (Nos.  30,  31,  32,  and  33.)  The  specimens 
Nos.  26,  27,  28,  and  29  are  of  similar  rocks  from  Logtown  and  vicinity. 
In  some,  hornblende  is  abundant,  and  in  others  augite  is  a  prominent 
constitutent;  in  still  others,  both  of  these  bi-silicates  appear.  Some  of 
the  rocks  have  abundant  free  quartz,  in  others  none  is  visible  to  the 
unaided  eye.  They  also  vary  greatly  in  the  kind  and  amount  of  feld- 
spars they  contain.  Southward  from  this  hill,  in  the  direction  of  the 
German,  Pocahontas,  and  Starlight  mines,  and  the  country  about  Log- 
town,  are  numerous  intrusive  dikes,  large  and  small,  of  rocks  of  the 
above  described  characteristics,  and  in  some  of  the  masses  rich  gold- 
bearing  deposits  or  veins  have  been  discovered  and  worked,  notably  in 
the  Pocahontas  at  Logtown.  In  the  neighborhood  of  Placerville  is 
found,  near  Diamond  Springs,  and  extending  nurthward  beyond  Placer- 
ville, another  section  of  the  great  dolomitic  vein  which  is  characteristic 
of  the  Central  Gold  Belt  in  Calaveras,  Tuolumne,  and  Mariposa  Counties. 
Here  is  seen  the  same  broad  zone  of  dolomite,  or  ankerite,  in  which 
occurs  an  abundance  of  the  beautiful,  scaly,  micaceous  mineral,  mari- 
posite.  Although  the  Pacific  Mine  in  Placerville  has  been  idle  and 
inaccessible  for  many  years,  the  old  dumps  clearly  show  the  character 
of  the  geological  formation.  In  this  mine  the  ankerite  has  been  com- 
pressed, sheared,  and  deformed,  the  original  material  being  altered  into 
a  perfect  talc  schist.  When  this  occurs,  mariposite  usually  disappears, 
or,  if  present,  cannot  longer  be  detected  by  its  characteristic  green  color. 
Serpentine  also  accompanies  this  belt,  which  is  not  an  uncommon 
accompaniment  southward.  In  the  Pacific  Mine,  the  serpentine  is 
frequently  found  altered  to  a  dark-green  talc  schist,  which  may  be 
readily  distinguished  from  the  white  schist  resulting  from  the  altera- 
tion of  the  dolomite. 

The  black  slates  found  associated  with  the  mineral  veins  between 
the  Cosumnes  River  and  Placerville  are  chiefly  the  result  of  the  altera- 
tion of  diabase  tuffs,  which  has  been  described  at  length  in  the  intro- 
ductory paragraphs    of   this  bulletin.     Mariposa  clay   slates  are  also 


90  CALIFORNIA    STATE    MINING    BUREAU. 

found.  Owing  to  the  very  unsettled  state  of  the  weather  and  the  diffi- 
culties and  delays  attending  transportation  in  March,  the  investigation 
of  this  section  was  not  carried  north  of  Placerville  until  the  summer 
season. 

German  Mine. — It  is  5  miles  south  of  El  Dorado.  This  was  the  first 
accessible  develojDed  mine  going  northward  last  spring  in  El  Dorado 
County  from  Amador  in  which  we  find  a  material  change  in  geological 
conditions.  The  general  formation  of  the  country  consists,  as  it  does 
farther  southward,  of  massive  diabase  tuffs,  amphibolite  schists,  and 
the  clay  slates  of  the  Mariposa  beds.  Here  we  also  find  the  black  slates 
resulting  from  the  alteration  of  the  diabase  tuffs  which  have  been  pre- 
viously described  as  being  intimately  associated  with  the  ore  deposits 
of  the  principal  mines  of  Amador  County.  The  gold-bearing  veins  of 
the  German  Mine  are  found  inclosed  in  these  tufaceous  slates,  and  the 
vein  structure  does  not  differ  materially  from  the  veins  of  Amador. 
The  clay  slates  of  the  Mariposa  beds  lie  both  to  the  eastward  and  to  the 
westward  of  the  main  fissure,  but  not  in  contact  with  it.  The  most 
striking  geological  feature  of  this  mine  is  the  intrusion  of  acidic  dikes, 
which  present  various  phases  ranging  from  quartz-porphyry  to  granite. 
There  were  evidently  several  intrusions  of  difierent  ages.  These  intruded 
dikes  have  been  sheared  and  have  suffered  deformation  in  a  manner 
similar  to  that  characteristic  of  the  altered  diabase.  These  dikes  in 
width  vary  from  a  few  feet  to  more  than  a  hundred  feet,  and  in  more 
than  one  place  the  larger  dikes  were  found  to  contain  zones  of  crushed 
material  into  which  free  silica  has  infiltrated,  together  with  iron  sul- 
phides and  gold,  but  to  what  extent  the  zones  are  gold-bearing  has  not 
as  yet  been  determined.  One  intrusive  mass  which  attracted  my  par- 
ticular attention  was  found  above  the  100-foot  level.  It  has  been 
intruded  from  the  southward  into  the  slates,  and,  as  viewed  in  the  mine 
excavations,  it  looks  like  the  stern  of  a  great  ship  as  it  appears  when 
lying  in  drydock.  A  banded,  slaty  vein  follows  around  this  peculiarly 
curved  intrusion,  having  the  granite  on  one  wall  and  the  slaty  tuffs  on 
the  other.  The  mine  is  equipped  with  a  water-power  hoist  and  a  mill 
of  10  stamps.  The  stamps  weigh  950  pounds,  and  drop  6  inches,  100 
times  a  minute.  The  discharge  is  7  inches  high,  and  a  30-mesh  brass 
wire  screen  is  used.  This  mill  has  a  capacity  of  3^  tons  per  stamp. 
Below  the  battery  plates,  a  shaking-riffle  table  has  been  introduced  for 
the  purpose  of  saving  any  amalgam  escaping  the  plates.  It  is  said  to 
give  satisfaction,  A  Wilfley  concentrator  is  employed  to  concentrate 
the  sulphurets,  which  constitute  about  H  per  cent  of  the  ore.     These 

are  shipped  to  Selby's  reduction  works. German  Mining  and  Milling 

Company  of  San  Francisco,  owners.  C.  0.  Richards  of  El  Dorado, 
superintendent. 


THE  MOTHER  LODE  REGION — EL  DORADO  COUNTY.  91 

Buena  Vista  Mine. — It  is  1  mile  east  of  the  German  Mine,  and  5 
miles  southerly  from  El  Dorado.  The  veins  are  found  in  Calaveras  for- 
mation— mica  schist  at  this  place.  A  small  vein  running  parallel  with 
the  strike  and  dip  of  the  schists  has  been  followed  for  some  distance  in 
search  of  pockets,  with  satisfactory  results.  A  former  operator  who 
prospected  this  mine,  in  some  way  was  misled  as  to  the  value  contained 
in  a  schistose  zone  impregnated  with  iron  sulphides,  and  expended 
nearly  .$50,000  on  the  property,  doing  considerable  development  work, 
erecting  numerous  buildings,  and  a  mill.  The  rock  proved  almost 
valueless,  and  the  mine  was  closed.     The  present  owners,  however,  are 

doing  well. C.  0.  Richards  of  El  Dorado,  owner.     Grant  Hill  of  El 

Dorado,  lessee. 

Last  Chance  Mine. — This  vein  is  1  mile  east  of  Nashville,  and  is  from 
1  to  8  feet  wide,  occurring  in  the  slates  of  the  Calaveras  formation.  The 
vein  has  a  beautiful  ribbon  structure,  and  has  been  developed  by  a  tun- 
nel driven  on  the  vein.  A  light-colored  dike  accompanies  the  vein.  The 
property  is  equipped  with  a  2-stamp  mill  run  by  gasoline  engine.     The 

property  is  idle. A.  C.  Smith  of  Portland,  Oregon,  owner.     H.  E. 

Smith,  in  charge. 

The  Center  Mine. — Owned  by  a  New  York  company,  and  is  near  the 
Last  Chance.     Idle. 

The  Nashville  Mine. — This  mine  is  south  of  the  Last  Chance,  and  is 

equipped  with  a  steam  hoist.     Idle. E.  J.  Baldwin  of  San  Francisco, 

owner. 

Madelina  Mine. — It  is  5  miles  south  of  Diamond  Springs.  This  vein 
or  zone  is  from  40  to  60  feet  in  width,  in  the  Calaveras  formation.  There 
is  a  gouge  and  dike  rock  on  the  foot-wall.  The  ore  is  pyrrhotite,  chalco- 
pyrite,  and  pyrite  with  gold.  The  ore  is  extremely  hard,  and  a  great 
portion  of  it  contains  a  very  large  percentage  of  the  sulphides  mentioned. 
It  offers  a  problem  in  economic  metallurgy.  The  vein  is  developed  by 
means  of  a  cross-cut  tunnel  90  feet  to  the  vein,  and  a  drift  along  the 
foot-wall  100  feet,  connected  by  a  raise  105  feet  to  the  surface. Will- 
iams &  Bier  of  El  Dorado,  owners. 

Noonday  Mine  (Copper). — This  property,  near  the  Madelina,  when 
visited,  was  simply  a  prospect  having  a  15-foot  shaft  and  several  open 
cuts  on  a  7-foot  vein  consisting  chiefly  of  iron  and  copper  sulphides,  the 
latter  ranging  from  a  trace  to  25  per  cent.  It  may  be  considered  a 
promising  prospect. Bonded  to  Dr.  Procter  of  Placerville. 

Montezuma  Mine. — At  Nashville.  This  property  after  an  idleness 
was  about  to  start  up  in  the  spring  of  1900. J.  C.  Heald  of  Nash- 
ville, owner. 


92  CALIFORNIA    STATE    MINING    BUREAU. 

Union  Mine. — It  is  3^  miles  southeast  of  El  Dorado.  It  was  formerly 
known  as  the  Springfield,  and  was  operated  by  Alvinza  Hayward  to  a 
depth  of  1700  feet.  Within  the  past  two  years  the  mine  has  been 
operated  by  a  company,  and  a  30-stamp  mill  built.  On  another  group 
of  mines  in  the  vicinity  a  new  shaft  was  being  sunk  in  March,  1900, 
and  though  less  than  100  feet  in  depth,  a  20-stamp  mill  was  being 
erected.  These  properties  are  under  the  management  of  A.  Harpending, 
and  were  the  only  ones  visited  during  the  season  where  inspection  was 
denied  and  information  refused.  It  was  currently  reported  that  a  large 
amount  of  gold  was  being  taken  out,  but  I  was  unable  to  confirm  this 
report.  There  are  45  men  employed  at  these  two  mines. A.  Har- 
pending of  El  Dorado,  superintendent. 

Church  Mine. — It  is  located  8  miles  south  of  Placerville,  and  2^  miles 
from  El  Dorado.  Three  veins  occur  in  the  slates;  they  are  well  defined, 
and  have  hard  walls  and  a  gouge  on  both  foot  and  hanging  walls.  The 
two  veins  mostly  developed  are  of  variable  thickness,  laminated,  and 
carrying  considerable  sulphurets.  There  is  also  an  east  vein,  known  as 
the  Union,  which  is  being  worked  near  the  south  end  of  the  property  on 
the  adjoining  Union  Mine.  Surface  prospects  on  this  lead  in  various 
places  give  a  result  of  from  $2.35  to  .$26  per  ton.  The  vein  worked  by 
the  former  company  was  termed  the  Kidney  vein,  and  has  been  worked 
to  a  depth  of  1350  feet,  taking  out  the  best  of  the  ore  and  leaving  the 
low-grade  ores.  This  vein  averages  5^  feet  in  width,  and  the  rock  taken 
from  it  milled  from  $28  to  $30  per  ton.  The  prospective  value  of  the 
mine  is  based  on  the  value  of  the  west  vein,  first  discovered  on  the  350- 
foot  level  while  sinking  the  shaft  on  the  Kidney  vein.  There  were 
milled  from  this  ledge  3000  tons  of  ore  taken  from  the  various  levels 
from  the  350-foot  to  the  1200-foot  level,  which  returned  $2.50  per  ton 
free  gold  and  about  2  per  cent  sulphurets,  worth  $67  per  ton;  the  tail- 
ings, owing  to  a  lack  of  facilities  in  the  mill,  averaged  $1.27.  This  vein 
in  many  places  is  from  14  to  20  feet  wide,  averaging  8  to  10  feet.  The 
main  shaft  is  1200  feet  deep  vertically,  with  a  40-foot  sump,  and  has 
three  compartments.  Stations  are  cut  at  each  level.  The  mine  is 
equipped  with  a  water-power  hoist,  and  is  provided  with  3000  feet  of 
steel  cable.  The  compressor  has  a  capacity  of  five  3-inch  drills.  The 
pumping  plant,  consisting  of  plunger  and  jack-head  pumps,  has  a 
capacity  of  150,000  gallons  per  day,  which  is  about  double  the  amount 
of  water  the  mine  makes.  The  mill  has  ten  950-pound  stamps,  four  Frue 
concentrators,  clean-up  barrel,  pans,  etc.  The  machinery  is  run  by 
water  power  taken  from  a  reservoir  owned  by  the  company;  at  the  mill 

there  is  a  head  of  485  feet. Church  Mine   Development  Company  of 

San  Francisco,  owners.     John  Ross,  Jr.,  of  Sutter  Creek,  superintendent. 

Griffith  Mine. — It  is  half  a  mile  southeast  of  Diamond  Springs  and 
half  a  mile  from  the  Larkin  Mine.     Since  the  last  report,  this  mine,  at 


THE    MOTHER   LODE    REGION — EL    DORADO   COUNTY.  93 

that  time  a  mere  prospect,  has  been  elaborately  equipped  with  hoist, 
mill,  etc.,  and  an  expensive  electric  power  plant,  by  a  Scotch  syndicate. 
After  a  few  months  of  active  operation,  the  mine  was  closed  down  and 
nothing  has  since  been  done  there.     It  is  locally  reported  that  it  did  not 

pay. Griffith  Mining  Company  of  Glasgow,  Scotland,  owners.     G.  P. 

Gow  of  Stent,  agent. 

Larhin  Mine. — One-half  mile  east  of  Diamond  Springs.  The  great 
dolomitic  vein  passes  through  this  property,  in  addition  to  which  there 
are  several  other,  though  less  prominent,  veins.  It  is  upon  one  of  the 
latter,  which  occurs  in  the  hanging-wall  slates  of  the  dolomitic  vein, 
that  operations  are  at  present  being  conducted.  This  vein  is  accom- 
panied by  a  small  dike  of  diabase,  and  possesses  the  usual  character- 
istics of  veins  in  slate.  The  dolomitic  vein  is  80  feet  in  width,  and  is 
altered  more  or  less  to  talc  schist.  The  dolomite  here  appears  to  contain 
iron  carbonate,  and  is  properly  ankerite  rather  than  dolomite.  The 
ankerite  vein  is  also  cut  by  dikes,  a  feature  not  observed  elsewhere,  and 
the  foot-wall  portion,  for  a  width  of  several  feet,  is  impregnated  with 
quartz  and  pyrite,  but  no  exploration  had  at  the  time  of  my  visit  been 
conducted  on  this  mineral  zone.  There  are  several  small  veins  in  the 
amphibolite  schist  of  the  foot-wall,  but  these,  too,  remain  unexplored. 
This  mine  has  a  10-stamp  mill,  the  stamps  weighing  1000  pounds,  drop- 
ping 110  times  a  minute.  A  No.  1  punched  tin  screen  is  employed. 
The  discharge  is  9  inches  high,  and  the  capacity  of  the  mill  under  these 
conditions  is  said  to  be  a  little  in  excess  of  3  tons  per  stamp  per  daj'  of 
twenty-four  hours.  The  ore  contains  14  per  cent  of  pyrites.  These  have 
been  shipped  to  Selby's,  but  experiments  with  the  cyanide  process  have 
demonstrated  that  the  gold  can  be  extracted  from  the  sulphides  by  this 
means  without  preliminary  roasting  or  other  treatment.  Of  the  gold 
obtained  by  amalgamation,  about  55  per  cent  is  recovered  in  the  battery. 

An  ingenious  experiment  has  been  tried  by  the  superintendent  with  a 
view  to  prevent  scouring  of  the  inside  copper  plates.  This  consists  of  a 
cast-iron  plate  having  the  shape  of  a  segment  of  a  cylinder  to  fit  the 
copper  plate.  It  is  \  inch  in  thickness,  with  slots  ^  inch  in  width  and 
20  inches  in  length.  Within  these  slots  the  amalgam  accumulates  and 
remains.  Concentration  is  accomplished  on  a  single  Wilfley  table.  A 
vertical  shaft  has  been  sunk  600  feet,  and  a  cage  is  in  use.     There  are 

35    men    employed. Larkin    Mining   Company   of    San    Francisco, 

owners.     G.  B.  Jacobs  of  Diamond  Springs,  superintendent. 

Selby  Mine. — It  is  1  mile  east  of  Diamond  Springs,  near  the  Larkin 
Mine.     Idle. 

Marguerite  Mine. — It  is  1  mile  east  of  Diamond  Springs,  near  the 
Larkin  Mine.     Idle. 


94  CALIFORNIA    STATE    MINING    BUREAU. 

Tin  Cup  and  Ribbon  Rock  Mines. — These  mines  are  2  miles  south  of 
Placerville,  and  are  being  operated  under  bond  by  A.  Hayward  of  San 
Francisco.  When  visited,  the  main  shaft  was  down  100  feet  in  "ribbon 
quartz  "  5  feet  wide  showing  gold,  and  for  amount  of  work  done  it  was 
considered  the  best  prospect  in  that  section  of  the  country.  There  are  10 
men  employed.  Since  writing  the  above  the  shaft  has  been  sunk  to  200 
feet  and  a  heavier  hoist  installed. E.  A.  Davis  of  Placerville,  super- 
intendent. 

Gentle  Annie  Mine. — It  is  1  mile  north  of  Placerville.  This  comprises 
a  property  1000  feet  by  1700  feet,  covering  five  parallel  veins,  of  which 
the  principal  one  appears  to  be  the  dolomitic  vein,  which  has  been  pre- 
viously described  as  characteristic  of  some  portions  of  the  Gold  Belt. 
The  mine,  while  extensively  developed  and  equipped  with  a  10-stamp 
mill,  has  been  idle  since  October,  1899,  awaiting  adjustment  of  the  affairs 
of  the  Melton  estate.     There  are  two  large  air-compressors  and  a  hoist, 

which  may  be  operated  by  either  water,  air,  or  steam. B.  G.  Parlow 

of  Placerville,  superintendent. 

Revera  Mine. — On  Texas  Hill,  3  miles  east  of  Placerville.  This  is  a 
drift  mine,  to  which  a  bedrock  tunnel  was  being  driven  900  feet  to  the 
channel,  which,  on  March  loth,  had  penetrated  a  distance  of  600  feet- 
The  property  is  equipped  with  a  mill  having  a  Dodge  pulverizer  with  a 
capacity  of  125  tons  daily,  running  15  revolutions  a  minute;  there  is 
also  in  the  mill  a  Krough  shaking-riffle.  The  mill  is  run  by  water  power 
under  169  feet  head.  A  self-discharging  tank  was  a  feature  of  the 
works,  so  arranged  as  to  sluice  out  accumulated  tailings.  Since 
writing  the  above  the  tunnel  has  reached  the  channel,  and  is  reported 
to  be  in  pay  gravel.  Parker  Bros,  of  Placerville,  owners.  C.  L.  Parker, 
superintendent. 

Ellen  Taylor  Drift  Mine. — It  is  4  miles  west  of  Indian  Diggings. 
Sluicing  and  piping  were  in  progress  in  the  spring  of  1900.    There  were 

11  men  employed. A.  B.  Spree kels  et  al.  of  San  Francisco,  owners. 

F.  J.  R.  Dawson,  superintendent. 

Umatilla  Drift  Mine. — This  is  in  El  Dorado  County,  12  miles  north- 
east of  Plymouth,  Amador  County.  The  mine  has  been  worked  steadily 
for  the  past  two  years.  The  gravel  channel  varies  greatly  in  width,  and 
ranges  from  a  few  inches  to  4  feet  in  thickness.  The  gravel  is  crushed 
in  a  Krough  hexagonal  mill,  similar  to  the  Dodge  pulverizer,  and  has  a 
capacity  of  250  tons  per  day.  Below  this  machine  is  a  shaking-riffle, 
in  which  the  gold  is  caught.     The  machinery  is  operated   by  water 

power. Umatilla  Mining  Company  of  San  Francisco,  owners.     C.  0. 

Richards  of  Ono,  superintendent. 

Placerville  Slate  Quarry. — It  is  1^  miles  north  of  Placerville.  Here  a 
quarry  has  been  opened  upon  a  reef  of  slate  150  feet  or  more  in  width. 


THE    MOTHER    LODE    REGION — EL    DORADO    COUNTY.  95 

standing  nearly  vertical.  A  large  portion  of  this  slate  appears  to  be  of 
merchantable  quality.  The  slate,  after  having  been  prepared  for  mar- 
ket, is  hoisted  to  the  top  of  the  hill  on  an  inclined  tramway,  the  car 
being  run  from  the  quarry  track  directly  upon  the  car  or  giraffe.  The 
tramway  is  double.  On  the  opposite  track  from  the  giraffe  is  a  car 
carrying  a  steel  cylinder  with  a  capacity  of  several  hundred  gallons. 
This  is  filled  with  water  at  the  top  of  the  incline,  and  when  its  weight 
overbalances  the  weight  of  the  giraffe,  carload  of  slate,  and  cable,  it 
moves  downward,  hauling  the  car  up  the  incline,  its  speed  being  con- 
trolled by  a  brake  at  the  head  of  the  tramway.  The  water  cylinder 
discharges  automatically  at  the  foot  of  the  incline,  when  the  giraffe  and 
car  return  to  their  places  at  the  loading  station.  This  company  has 
taken  contracts  to  furnish  slate  for  the  buildings  of  the  Mountain  Cop- 
per Company  at    Keswick,  Cal.;    for  the  Government,  and   elsewhere. 

There  are   10   men   employed. Placerville  Slate  Company,  owners. 

G.  W.  Cummings  of  Placerville,  manager, 

Pocahontas  Mine. — It  is  3  miles  south  of  El  Dorado.  The  vein, 
which  lies  at  a  low  angle  with  a  curving  strike,  occurs  in  a  feldspathic 
porphyry  (No.  26),  through  which  is  scattered  many  crystals  of  bronze- 
colored  mica.  This  peculiar  rock  when  examined  in  sections  under  the 
microscope  is  seen  to  be  a  diorite-porphyrite.  The  property  was  at  one 
time  well  equipped  with  machinery,  having  hoisting  works  and  a  10- 
stamp  mill,  but  these  have  been  removed  and  the  mine  has  been  idle 

for  some  time,  although  at  one  time  producing  handsomely. Q.  A. 

Chase  of  San  Francisco,  owner. 

Minnehaha  Mine. — This  is  3  miles  south  of  El  Dorado  P.  0.,  near 
Logtown.  The  vein  occurs  in  quartz-porphyry  much  silicified,  and 
containing  a  small  amount  of  iron  sulphide  Avith  coarse  free  gold.  The 
vein  strikes  N.  W.  and  dips  N.  E.  about  10  degrees  below  the  horizon. 
There  is  no  parting  between  the  vein  and  the  country  rock,  the  ore 
passing  over  gradually  to  the  country  rock.  In  one  place  along  the 
surface  in  the  hanging-wall  was  found  a  zone  of  porphyry  with  many 
quartz  seams  carrying  gold.  These  were  dipping  toward  the  flat  vein, 
but  had  not  been  reached  in  the  mine  workings.     The  rock  is  crushed  in 

a  4-stamp  mill.     No  concentrators  were  in  use;   8  men  employed. 

Minnehaha  Gold  Mining  Company  of  San  Francisco,  owner.  Froehlich 
&  Perham  of  El  Dorado,  lessees. 

Starlight  Mine. — Three  miles  south  of  El  Dorado.  The  ore  in  this 
mine  occurs  in  large  lenses  in  a  much  altered,  silicified  diabase.  There 
are  several  shafts  on  the  mine  provided  with  steam  hoists,  and  there  is 
a  10- stamp  steam  mill,  which  is  supplied  with  ore  from  the  several 
shafts  by  means  of  a  rope  tramway,  having  a  capacity  of  35  tons  a  day. 
The  ten  stamps  weigh  1000  pounds  each,  and  drop  6  inches  100  times  a 


96  CALIFORNIA    STATE    MINING    BUREAU. 

minute.  The  discharge  is  7|  inches  high.  A  No.  8  vertical-slot  screen 
is  employed.  Concentration  is  eftected  by  the  use  of  two  Union 
machines  and  a  canvas  plant.  The  ore  contains  2  per  cent  of  sul- 
phurets — pyrite,  galena,  and  arsenical  sulphide.  The  value,  how- 
ever, is  chieHy  in  free  gold. Starlight  Gold  Mining  Company  of  San 

Francisco,  owners.     J.  A.  Vance  of  El  Dorado,  superintendent. 

Oro  Fino  Mine. — This  property,  which  has  been  repeatedly  described 
in  former  reports,  was  found  working  as  usual.  It  is  situated  5  miles 
south  of  Diamond  Springs.  The  vein,  which  is  40  feet  wide,  consists  of 
a  dike-like  mass  of  diabase  breccia  Avhich  has  become  silicified  and 
impregnated  with  finely  disseminated  auriferous  pyrite.  Many  small 
seams  of  calcite  traverse  the  rock  in  every  direction.  Both  hanging 
and  foot-wall  country  are  diabase,  but  little  altered  even  in  close  prox- 
imity to  the  vein.  The  vein  material  is  extremely  hard,  and  all  ground 
is  broken  by  machine  drills,  No.  1  Judson  powder  being  used.  A 
vertical  shaft  has  been  sunk  to  a  depth  of  200  feet,  where  it  turns  at  an 
angle  of  40  degrees  and  continues  to  a  depth  of  540  feet  on  the  vein. 
The  hoist  is  operated  by  compressed  air.  The  mine  has  a  mill  of  30 
stamps,  which  weigh,  when  newly  shod,  1250  pounds.  These  drop  7 
inches  105  times  a  minute.  A  40-mesh  punched  tin  screen  is  used,  the 
capacity  of  the  mill  being  85  tons  daily.  No  amalgamation  is  attempted 
inside  the  batteries.  About  one  third  of  the  values  are  in  free  gold, 
which  is  collected  on  the  outside  plates.  The  sulphides  are  concen- 
trated on  belt  machines,  and  are  treated  in  a  chlorination  plant  owned 
by  the  company.  Its  daily  capacity  is  4  tons.  A  rotary  conical 
breaker  of  the  Gates  type,  being  cast  extremely  heavy,  has  been  found 
satisfactory   in    crushing   this   unusually  hard  rock.     This   mine   has 

recently    been    shut   down. Hay  ward   &   Lane   of    San    Francisco, 

owners.     E.  T.  Kane  of  Canyon  P.  0.,  superintendent. 

Vandalia  Mine. — This  interesting  mine  is  situated  about  half  a  mile 
northerly  from  the  Oro  Fino.  It  has  come  into  renewed  prominence 
since  the  publication  of  the  last  report.  In  many  respects  it  is  entirely 
unlike  others  of  the  Gold  Belt,  though  mines  of  somewhat  similar 
character  are  known  in  Arizona,  Nevada,  and  other  portions  of  the 
Great  Basin  country.  A  description  of  the  old  Vandalia  Mine  will  be 
found  in  the  Vlllth  report  of  the  State  Mineralogist.  When  being 
worked  at  that  time,  the  ore  was  considered  free  milling,  but  still  so  large 
a  percentage  of  the  values  was  lost  in  tailings  that  the  character  of  the 
mine  was  essentially  the  same  then  as  now,  though  richer.  The  large 
ore-shoots  developed  by  the  present  owners  are  not  amenable  to  amal- 
gamation, but  the  cyanide  process,  which  has  been  applied  in  a  rather 
rudimentary  manner,  has  been  found  to  operate  satisfactorily. 

When  the  present  owners  first  visited  the  property,  they  tested  the 
old  tailings  dumps  which  resulted  from  the  operations  of  former  owners. 


THE   MOTHER   LODE   REGION — EL   DORADO   COUNTY.  97 

and  these  were  found  to  contain  upward  of  $15  per  ton  in  gold.  A 
series  of  cyanide  experiments  soon  demonstrated  the  adaptability  of  this 
ore  to  that  process.  The  tailings  dumps  were  first  worked,  and  paid 
handsomely.  Then  the  ore-bodies  were  attacked,  and  work  has  con- 
tinued uninterruptedly  since. 

The  ore  deposits  are  found  in  a  highly  silicious  felsite,  having  a 
semi-schistose  structure,  and  in  many  respects  are  not  unlike  the  quartz 
schists  found  in  the  Calaveras  formation,  though  these  latter  are  gen- 
erally metamorphosed  sandstones,  and  not  of  intrusive  origin.  The 
ore-shoots  average  over  80  feet  in  width  and  300  feet  in  length,  and  cut 
both  the  strike  and  dip  of  the  inclosing  formation.  The  normal  ore  is 
essentially  the  quartz  schist  above  described,  heavily  impregnated  with 
iron  sulphide,  the  oxidation  of  which  has  produced  a  mineralized  zone 
extending  from  the  surface  to  a  depth  of  100  feet  or  more,  forming  a 
reddish-brown  iron  cap  or  gossan.  These  ore-shoots  are  reached  through 
adit  tunnels,  the  lowest  of  which  will,  when  extended,  cut  the  ore-bodies 
300  feet  below  their  apex,  and  tunnels  may  be  run  at  still  lower  points. 
The  ore  for  most  part,  though  heavily  mineralized  and  oxidized  near 
the  surface,  does  not  prospect  at  all  in  free  gold,  but  always  assays. 

The  mill  found  in  operation  at  this  mine  was  of  home  construction, 
made  by  the  owners  themselves,  and  is  a  rude,  though  ingenious  affair,  but 
not  well  suited  to  the  class  of  work  it  is  required  to  perform.  It  consists 
essentially  of  a  revolving  hollow  cylinder  resting  upon  four  wheels  or 
carriers,  and  provided  with  iron  bars  arranged  transversely  to  its  length, 
having  about  -|  inch  space  between  them,  similar  to  the  Dodge 
pulverizer.  In  the  interior  of  this  cylinder  are  three  so-called  cams, 
which  are  really  elevated  ribs  extending  lengthwise  of  the  cylinder  and 
distributed  at  equal  distances.  The  crushing  device  consists  of  three 
cylinders  of  iron,  each  10  inches  in  length  and  8  inches  in  diameter. 
These  are  connected  at  their  ends  by  links,  iron  rods  extending 
outwardly  from  each  end  of  the  connected  cylinders  to  posts  situated 
outside  the  machine.  As  the  cylinder  revolves,  the  cams,  each  in  turn, 
lift  the  linked  crushers  until,  clearing  themselves,  they  fall  backward  a 
few  inches,  crushing  the  soft  ore;  this  being  repeated  as  long  as  the 
machine  is  in  operation.  The  rock  is  fed  through  the  open  end  of 
the  cylinder,  passing  out  between  the  bars,  when  crushed  fine  enough  to 
pass  the  half-inch  space  between  them.  The  machine  is  driven  by  a 
belt,  power  being  furnished  by  a  gasoline  engine.  As  a  result  of  this 
very  coarse  crushing,  extraction  of  gold  rarely  exceeds  60  per  cent. 

The  cyanide  plant  is  situated  about  200  feet  from  the  mill,  at  the  foot 
of  an  inclined  tramway.  The  plant  consists  of  two  clear-water  tanks, 
two  stock-solution  tanks,  six  percolation  vats  of  10  tons  capacity  each, 
two  gold-solution  tanks,  and  two  sump  tanks,  together  with  the  neces- 
sary precipitation  boxes.     The  ore  from  the  mill  is  delivered  to  the 

7 — MB 


98  CALIFORNIA   STATE   MINING   BUREAU. 

cyanide  plant  by  cars  running  on  a  double  tram,  the  cars  working  in 
balance.  Between  the  line  of  percolation  tanks  is  a  track  running  the 
full  length  of  the  plant,  with  a  turntable  at  the  center.  The  ore  is 
dumped  directly  into  the  tanks,  and  distributed  by  shoveling  at  a  cost 
of  25  cents  per  ton,  including  the  cost  of  tramming.  The  cyanide  solu- 
tion is  worked  at  about  0.25  per  cent,  with  a  consumption  of  15  per 
cent  cyanide.  The  ore  is  charged  as  described,  and  the  solution  turned 
in  on  top  of  the  charge  upon  burlaps.  It  is  allowed  to  stand  three 
hours,  when  a  valve  is  opened,  and  a  pump  connected  with  the  weak 
solution  in  the  sump  tanks  is  started.  This  solution  is  pumped  on  at 
a  rate  equaling  the  progress  of  leaching,  until  the  amount  of  solution 
charged  is  equal  to  the  weight  of  the  ore.  The  percolation  process  is 
usually  completed  in  forty-eight  hours.  In  the  bottom  of  the  precipi- 
tating-box  an  ordinary  punched  tin  mill  screen  is  placed,  which  keeps 
perfectly  clean  and  shows  no  sign  of  corrosion.     The  cost  of  treatment 

is  stated  by  the  owners  to  be  50  cents  per  ton. Seymour  &  Staver, 

owners  and  managers,  Shingle  Springs  P.  0.  It  is  stated  that  this  mine 
has  recently  passed  into  other  hands,  and  is  to  be  extensively  equipped 
and  operated. 

Fortuna  Mine. — It  is  5^  miles  south  of  Shingle  Springs,  near  the  Oro 
Fino  Mine.  At  the  time  of  my  visit  last  spring,  the  mine  and  5-stamp 
mill  were  idle,  but  the  owners  were  building  a  ditch  in  anticipation  of 
resuming  operations. Hale  &  Boughman  of  Canyon  P.  O.,  owners. 

Monitor  Mine. — It  is  3  miles  south  of  Canyon  P.  0.  The  vein  occurs 
at  contact  of  slate  and  greenstone.  It  has  a  shaft  60  feet  deep,  with  a 
50-foot  drift  at  the  bottom.     The  vein  is  7  feet  wide,  and  the  rock  is  said 

to  mill  $6  per  ton.     The  mine  is  provided  with  a  steam  hoist. C.  E. 

Schenks  of  Canyon  P.  O.,  owner. 

Spanish  Dry  Diggings. — At  this  place,  ^  mile  northwest  of  Greenwood, 
a  few  men  are  making  a  living  working  the  rich  seams.  No  organized 
operations  are  in  progress. 

Altman  Mine. — Near  Greenwood.  The  property  comprises  3000  feet 
on  the  lode.  The  principal  development  consists  of  a  tunnel  500  feet 
long,  which  gives  250  feet  backs.  The  mineralized  zone  is  about  100 
feet  wide,  and  is  stated  to  mill  -$3  per  ton.  A  strip  along  the  foot-wall, 
however,  runs  much  higher.  A  10-stamp  mill  formerly  on  the  property 
burned.     Two  men  are  at  work John  Smith  of  Greenwood,  owner. 

Gopher-Boulder  Mine. — It  is  1  mile  north  of  Kelsey.  The  property 
was  well  equipped  with  electric  power,  but  the  generator  house  on  Rock 
Creek  burned.  This  is  to  be  replaced.  The  mill  contains  20  stamps  and 
two  5-foot  Huntington  mills;  these  latV5r  are  stated  to  be  equal  to  the 
20  stamps  in  capacity.  The  vein  is  frAm  30  to  100  feet  wide,  but  low- 
grade.  A  shaft  has  been  sunk  on  the  ^jein  250  feet,  and  a  large  open  cut 
has  been  made  in  a  zone  of  quartz  and  greenstone  schist.     Mining  can 


THE    MOTHER   LODE    REGION EL    DORADO    COUNTY.  99 

be  carried  on  here  very  cheaply,  as  the  company  owns  its  power.  At 
the  Dalmatia,  a  mile  distant,  mining  and  milling  were  formerly  carried 
on  at  a  cost  below  50  cents  per  ton.     The  Gopher-Boulder  is  idle,  but  it 

was  stated  that  work  would,  in  all  probability,  soon  be  resumed. W. 

A.  Bell  of  San  Francisco,  owner.     W.  H.  Husband  of  Kelsey,  manager. 

Hayward  Hydraulic  Mine. — At  Indian  Diggings,  on  an  ancient  channel. 
There  is  about  150  feet  of  gravel,  overlaid  by  over  100  feet  of  volcanic  ash . 
The  mine  was  extensively  worked  during  the  spring  and  summer  seasons 
by  hydraulic  methods.  About  1000  inches  of  water  is  employed  in 
washing. Plymouth  Consolidated  Mining  Company,  owners. 

Eureka  {Strale)  Slate  Quarry. — This  property,  situated  near  the  vil- 
lage of  Kelsey,  was  in  operation  during  the  summer,  employing  20  men. 
Steam-operated  power  drills  are  in  use.     A  superior  quality  of  slate  is 

produced   at  this  quarry. Eureka   Slate  Company,  owner.     W.  A. 

Winsboro  of  Kelsey,  superintendent. 

Zantgraf  Mine. — It  is  7^  miles  east  of  Newcastle,  Placer  County,  and 
has  been  in  operation  for  fifteen  years.  The  principal  shaft  is  sunk  at 
an  angle  of  45  degrees  in  grano-diorite.  It  is  1125  feet  deep.  There  are 
10  levels  open  in  the  mine.  Power  drills  are  employed.  Two  shoots  of 
good  ore  are  on  the  main  fissure,  with  300  feet  of  low-grade  rock  inter- 
vening. On  the  300-foot  level  a  cross-cut,  run  150  feet  west,  encountered 
a  parallel  vein,  in  which  a  shoot  of  pay  rock  has  been  developed.  The 
sulphides,  constituting  -i  of  1  per  cent,  are  high-grade,  and  with  increas- 
ing depth  it  is  stated  that  the  percentage  of  sulphurets  increases  with- 
out any  noticeable  decrease  in  free  gold.  The  north  shoot  on  the  main 
vein  has  been  explored  for  a  distance  of  300  feet,  and  the  face  is  still  in 
good  ore.  The  same  shoot  is  being  opened  on  the  300-foot  level,  where 
it  is  600  feet  long,  and  is  also  being  developed  on  the  700  and  800  levels. 
On  the  1100-foot  level  the  shaft  is  in  low-grade  rock,  but  the  north  shoot 
is  expected  at  the  1200,  as  it  is  pitching  south.  It  is  150  feet  from  the 
shaft  to  the  south  shoot.  The  property  is  equipped  with  25-stamp  mill, 
and  has  a  duplicate  steam  plant  for  both  hoist  and  mill,  though  depend- 
ing, under  ordinary  conditions,  upon  electric  power.  The  company  owns 
its  power  plant,  whicli  is  located  on  the  American  River  half  a  mile 
distant  from  the  mine.  The  machinery  was  being  renewed  the  past 
summer  at  the  time  of  my  visit.  The  stamps  in  the  mill  weigh  1035 
pounds,  when  new.  A  punched  tin  screen  is  in  use;  the  capacity  is 
about  5  tons  per  stamp,  with  a  discharge  5  to  6  inches  high.    This  large 

capacity  is  due,  of  course,  to  the  unusually  coarse  screen. ^ Montauk 

Gold    Mining  Company  of  New  York,  owners.     Edward  Goodwin  of 
Newcastle,  superintendent. 

Jack  Hanley  Mine. — It  is  2^  miles  south  of  Greenwood.     Prospecting 

is  in  progress.     A  rocking  mill  is  in  use.     Four  men  are  employed. 

C.  A.  La  Graves  of  Greenwood,  superintendent. 


100  CALIFORNIA    STATE   MINING   BUREAU. 


CALAVERAS  COUNTY. 


In  this  county  the  mining  industry  is  unusually  prosperous,  more  so 
than  in  many  years  past.  There  are  at  work,  and  paying,  no  less  than 
a  dozen  large  mines,  including  three  hydraulic  mines,  besides  a  great 
many  small  concerns,  and  a  good  deal  of  active  prospecting  is  now 
in  progress.  Since  the  last  report,  a  number  of  new  enterprises 
have  started  up  which  are  now  idle,  having  proven  unsatisfactory  to 
the  investors,  but  there  are  others  which  have,  in  a  great  measure, 
redeemed  these  more  unfortunate  ventures.  Notable  among  the 
latter  class  is  the  Sheep  Ranch  Mine,  which,  after  an  idleness  of 
nearly  six  years,  has  been  reopened,  and  is  again  an  active  and,  it  is 
said,  a  profitable  producer.  The  copper  mines  at  Campo  Seco  are  also 
being  operated  successfully,  and  in  the  Salt  Sp'ring  Valley  at  Hodson 
the  Royal  Consolidated  Mines  are  being  worked  on  a  much  larger  scale 
than  heretofore.  On  the  whole,  Calaveras  County  may  be  said  to  be  in 
a  very  prosperous  condition.  The  development  and  exploitation  of  the 
new  ore-bodies  found  in  the  Utica-Stickle  and  Gold  Cliff  properties  at 
Angels  will  give  a  new  lease  of  life  to  these  important  producers,  and 
the  operations  of  the  Melones  Consolidated  Mining  Company  at  Carson 
Hill  will  be  among  the  most  extensive  in  the  State  when  carried  to 
completion. 

Gwin  Mine. — It  is  6  miles  south  of  Jackson,  Amador  County.  In 
its  earlier  history  this  mine  was  worked  to  a  depth  of  1540  feet  through 
inclined  shafts.  Operations  were  suspended  in  the  fall  of  1882,  and  the 
property  remained  idle  until  1894,  when  the  present  operators  reopened 
the  mine.  A  vertical  shaft  was  started  in  the  hanging-wall  slates  485 
feet  from  the  vein.  Work  was  commenced  on  May  1,  1894,  and  has 
progressed  continuously  since,  with  the  exception  of  a  period  of  about 
four  months,  when  an  attempt  was  made  to  unwater  the  old  workings 
by  means  of  a  bore-hole  to  avoid  flooding  of  the  new  workings  from 
the  old.  It  eventually  became  necessary  to  remove  the  water  through 
the  shaft  of  the  old  workings.  This  new  shaft  has  continued  to  a  depth 
of  1660  feet,  having  passed  through  the  vein  at  about  the  1200-foot  level. 
There  are  tanks  at  the  300-foot  level  and  at  the  700-foot  level.  At  the 
latter  a  cross-cut  was  run  west  from  the  station  374  feet,  through  slate 
to  and  beyond  the  vein,  the  foot-wall  of  which  was  reached  124  feet 
west  of  the  shaft.  At  the  1000-foot  level  a  cross-cut  was  run  69  feet 
west  through  the  vein,  which  was  here  15  feet  6  inches  wide,  the  foot- 
wall  being  58  feet  west  of  the  shaft.     The  foot-wall  of  the  vein  was 


THE  MOTHER  LODE  REGION — CALAVERAS  COUNTY. 


101 


encountered  in  the  shaft  1245  feet  from  the  surface.  Cross-cuts  in  the 
lower  levels  run  to  the  westward  have  encountered  two  small  veins 
and  two  dikes  of  light-gray  intrusive  rock.  The  first  vein  encountered 
is  very  persistent  in  strike  and  dip,  though  usually  small.     It  has  pro- 


WFWW/ili 


MEtTHOD     of    T)N^3£RIN<^     in     (5\A/1N   A^lNErr 

FiG.  28. 

duced  some  rich  ore.  The  ore-shoots  of  the  main  vein  are  of  great 
length,  varying  in  width  from  a  few  inches  to  20  feet.  Gouge  is  always 
present  on  the  foot,  and  sometimes  on  the  hanging-wall.  The  slates 
have  a  tendency  to  swell,  and  are  the  cause  of  considerable  expense, 


102  CALIFORNIA   STATE   MINING   BUREAU. 

but  cannot  be  compared  in  this  respect  to  some  of  the  Amador  County 
mines.  The  vein  is  usually  banded,  and  exhibits  a  branching  tendency, 
there  being  many  spurs  running  into  the  hanging-wall,  but  few  into  the 
foot.  The  lenses  of  quartz  which  are  characteristic  of  this  vein  fre- 
quently build  up  a  narrow  into  a  large  vein  by  splicing,  and  sometimes 
by  overlapping.  There  is  some  black  slaty  material  in  the  vein,  but 
less  than  is  found  in  many  similar  mines  elsewhere.  Large  masses  of 
the  vein  quartz  are  found  crushed  by  pressure  and  movement,  and  in 
some  places  the  quartz  disintegrates  rapidly  from  exposure  by  reason  of 
the  slaking  of  the  carbonate  of  lime,  which  occurs  in  considerable 
quantities. 

The  mine  is  systematically  opened,  and  substantially  timbered  with 
Oregon  pine.  The  framing  of  timber  is  mostly  done  by  machinery. 
Filling  for  the  stopes  is  usually  obtained  from  the  hanging-wall,  and 
broken  by  machines  in  chambers  excavated  for  the  purpose.  Where 
feasible,  inclined  raises  are  put  into  the  hanging-wall,  and  the  chambers 
opened  out  from  the  raise,  the  rock  broken  passing  by  gravity  down  the 
incline  into  the  stopes  beneath.  Where  the  character  of  the  hanging- 
wall  adjacent  to  the  vein  is  such  as  to  cause  the  ground  to  cave  readily, 
level  cross-cuts  are  run  from  the  stopes  into  the  hanging-wall,  and 
chambers  opened  out  at  a  safe  distance  from  the  vein,  the  filling  being 
carried  to  the  stopes  in  wheelbarrows.  The  Gwin  Mine  is  one  of  the 
best  managed  properties  it  was  my  pleasure  to  visit,  everything  being 
done  systematically  with  a  view  to  producing  the  best  economic  results. 
The  sketch  (Fig.  28)  represents  the  method  of  timbering  stopes  in  the 
Gwin  Mine.  I  was  told,  when  at  the  mine,  that  the  management  had 
under  consideration  the  advisability  of  running  a  lateral  drift  in  the 
foot-wall,  and  opening  the  mine  something  on  the  lines  suggested  in  the 
first  part  of  this  bulletin,  under  the  head  of  "  Methods  of  Mining." 

Geologically,  the  Gwin  Mine  presents  a  striking  contrast,  when  com- 
pared with  the  more  important  mines  of  Amador  County.  Here  the 
vein  occurs  in  the  smooth,  satin-like  clay  slates  of  the  Mariposa  beds, 
which  are  absolutely  free  from  the  pitted  appearance  so  characteristic 
of  the  slates  accompanying  the  ore-shoots  of  Amador  County,  which  have 
been  fully  described  under  the  head  of  Amador  County,  and  also  under 
the  head  of  "  General  Geology  of  the  Gold  Belt."  The  formations 
encountered  in  sinking  the  Gwin  shaft  are  diabase-tuff,  clay  slates,  and 
small  acid  dike  rocks.  In  the  lower  portion  of  the  mine,  a  coarse, 
tufaceous  rock,  locally  but  erroneously  called  pudding-stone,  has  been 
encountered,  which  has  been  the  cause  of  considerable  difficulty  in 
timbering,  in  carrying  on  mining  operations.  It  is  the  intention  of  the 
company  to  make  some  changes  in  their  shaft,  and  to  sink  to  greater 
depth.  What  may  be  developed  in  this  property  at  great  depth  is  a 
matter  of  more  than  ordinary  interest.  Its  present  lowest  level  still 
lacks  about  1000  feet  of  being  as  deep  as  the  Kennedy,  and  it  is  a  well- 


THE    MOTHER    LODE    BEGION — CALAVERAS   COUNTY. 


103 


Wedic 


known  fact  that  the  ore-bodies  in  the  lowest  workings  of  the  latter  show 

no  deterioration  in  value. Gwin  Mine  Development  Company  of  San 

Francisco,  owners.     J.  J.  Crawford,  secretary,  Spreckels  Building,  San 

Francisco;  F.  F.  Thomas,  Gwin  Mine,  Calaveras 
County,  superintendent. 

Gtoin  Mill. — The  mill  at"  the  Gwin  Mine  now 
comprises  80  stamps,  and  is  operated  under  the 
direction  of  Mr.  J.  E.  Taylor.  The  stamps  when 
new  weighed  850  pounds,  and  drop  6^  inches  92 
times  per  minute.  The  height  of  discharge  is  from 
7  to  9  inches,  and  is  regulated  by  three  chuck- 
blocks.     No.  16  brass  wire  screens  are  in  use,  and 

last   one  month.     The  screens 
6ci?£C-iM  Ff?aM£    s-i'®    changed    daily,    scrubbed 

and  dried,  so  that  practically 
the  screens  are  daily  as  good  as 
Qy^ucK  ^L.Ocy(  new,  until  worn  oiit.  The  size 
(^wiN  NJiNfe:  of  the  screen  opening  is  5  inches 
by  48  inches  (discharge  area). 
All  screens  are  secured  to  small  frames,  which  are 
inserted  above  the  chuck-block  and  beneath  the 
front  board  of  the  main  screen  frame,  being  secured 
by  a  wedge.  (See  sketch,  Fig.  29.)  The  capacity 
of  the  mill,  under  the  above  conditions,  is  4i  tons 
per  stamp  daily.  To  prevent  scouring  of  the  inside 
plate  an  iron  rod  is  bolted  to  the  plate.  Its  posi- 
tion is  shown  in  the  figure.  The 
pulp  from  the  battery  falls  onto  the 
iron  lip  of  the  mortar,  thence  by  a 
3-inch  fall  onto  a  narrow  board,  and 
(ronfiar  ^^j^ence  outo  the  apron  plates,  which 
are  48  x  60  inches,  set  at  the  grade 
of  2  inches  to  the  foot.  Thence  it 
passes  to  the  sluice  plates,  which  are 
24x120  inches,  having  at  the  end 
a  trap  for  the  purpose  of  catching 
mercury  and  amalgam.  From  the 
plates,  the  pulp  passes  to  the  van- 
ner  distributers,  and  from  the  van- 
ners  the  tailings  go  to  waste.  In 
the  canon  some  distance  from  the 
mill  a  canvas  plant  was  constructed 
by  experimenters,  some  time  since,  but  its  use  was  discontinued.  The 
sulphides,  collected  on  the  vanners,  are  heavy,  probably  coming  from 
the  quartz,  and  the  values  from  the  sulphides  are  largely  confined  to 


Fig.  29. 


104  CALIFORNIA   STATE    MINING   BUREAU. 

this  class  of  material.  A  quantity  of  fine  sulphides  escapes  with  the 
tailings,  which  probably  come  from  the  slaty  material.  They  are  low- 
grade,  and  do  not  even  justify  the  inexpensive  further  concentration  on 
canvas  tables. 

The  concentration  plant  consists,  in  the  original  mill,  of  sixteen 
4- foot  Frue  vanners,  one  of  which  is  of  special  design  called  the  "  Gwin." 
In  the  40-stamp  addition  recently  made  to  the  mill  there  are  sixteen 
6-foot  machines,  all  of  this  special  design.  These  machines  have  an 
iron  frame  with  cross-rods  both  longitudinally  and  transversely  of  the 
machine,  which  gives  it  great  rigidity,  and  demands  little  attention 
when  having  been  properly  adjusted.  The  sulphides  contained  in  the 
ore  range  from  14  to  2  per  cent.  These  are  shipped  to  Selby's  reduction 
works.  Mr.  Taylor  states  that  the  tailings  escaping  from  this  mill 
average  about  25  cents  per  ton.  The  entire  plant  is  run  by  water 
power,  under  a  400-foot  head.  A  6-foot  Pelton  wheel  runs  the  80 
stamps,  and  a  24-inch  wheel  the  concentrating  machines.  Power  is  dis- 
tributed from  the  line  shaft,  which  is  beneath  the  feeder  floor,  by  vertical 
belts  to  the  cam-shaft  pulley.  The  power  is  transmitted  from  the  main 
wheel  to  the  line  shaft  by  a  hemp  rope  5  inches  in  circumference. 
Space  has  been  provided  in  the  building  for  an  additional  20  stamps,  for 
which  there  is  abundant  power.  An  electric  plant  has  been  installed 
for  lighting  the  property.  The  mortars  in  the  old  mill  differ  somewhat 
from  those  in  the  new  mill,  those  in  the  new  mill  being  narrower.  The 
mortars  are  lined  throughout  with  deep  plates  and  are  thoroughly 
modern. 

Sheep  Ranch  Mine. — This  is  at  Sheep  Ranch  and  on  the  east  belt,  17 
miles  northeast  of  San  Andreas.  The  mine  was  operated  in  former  days 
by  Haggin,  Tevis,  and  Hearst,  but  was  closed  down  in  1893,  when  a 
depth  of  1200  feet  had  been  reached,  after  producing  about  -$3,000,000. 
It  remained  idle  until  1898,  when  it  was  reopened  by  the  present  owners, 
who  cleaned  out  the  old  shaft,  retimbered  it,  installed  a  new  and  heavy 
plant  of  machinery,  and  thoroughly  equipped  the  mine,  in  the  belief 
that  it  was  not  exhausted.  They  went  into  the  old  workings  on  the  1200- 
foot  level;  extended  them;  drove  the  Pioche  tunnel  to  a  connection  with 
the  shaft  at  the  300-foot  level,  and  started  upraises  at  various  points  on 
the  1200-foot  level,  and  began  at  once  taking  out  rich  ore.  A  new  20- 
stamp  mill  has  been  built;  two  air-compressors,  and  an  electric  plant 
and  machine  shop  have  been  provided.  The  property  comprises  twenty- 
one  claims,  which  include  five  known  veins.  The  formation  is  a  rather 
coarse  mica  schist,  cut  by  dikes  of  diorite  and  coarse-grained  granite. 
The  Sheep  Ranch  vein,  which  is,  so  far  as  known,  the  hanging- wall  vein 
of  the  series,  is  from  a  few  inches  to  3  feet  in  width,  averaging  about  18 
inches.  The  ore  is  generally  high-grade,  often  showing  free  gold,  one 
shoot  in  particular  now  being  operated  south  of  the  shaft  above  the  1200- 


THE    MOTHER    LODE    REGION — CALAVERAS    COUNTY. 


105 


foot  level,  producing  a  dark  blue,  almost  black,  quartz,  rich  in  free  gold. 
The  most  of  this  rock  is  in  demand  by  the  manufacturers  of  jewelry,  it 
thus  paying  far  better  than  to  crush  it  in  the  mill.  The  quartz  usually 
occurs  as  a  continuous  waving  vein,  or  as  a  succession  of  disconnected 
lenses,  often  contorted  and  twisted  suddenly  from  its  course,  and  when 
this  occurs  visible  gold  is  usually  abundant. 

The  accompanying  sketch    (Fig.  30)  represents  a  characteristic  sec- 

\\»U\\\#i\\\\\\\A\\\\\' 


\ 


\V, 


^A  u  ,\ 


W 


V 


\\\^j  i  \ 


\^VA\S\ 


\\\h\\ 


\\\\\\\V\\ 


Wm\ 


mmm 

200-({-Lt\/E 


\\\\\\\WX\\ 

Vertical  Cross  SecVion 

o!^  ^MEE-P    I^ANdH    /^INE-     shoWii^°    charac^'eris'Ti  d, 

Veir\  Pornr^a-Hor^. 

Fig.  30. 


tion  of  the  Sheep  Ranch  vein.     Each  of  the  several  veins  in  this  prop- 
erty has  considerable  superficial  development. 

A  shaft  is  being  sunk  on  the  Lodi  claim,  one  of  the  Sheep  Ranch 
group,  about  700  feet  southwest  of  the  main  shaft.  It  is  said  that  in 
former  years  very  rich  ore  was  taken  from  the  Lodi  vein.    All  machinery 

at  the  Sheep  Ranch  is  operated  by  steam. Sheep   Ranch  Mining 

Company,  owners,  320  Sansome  Street,  San  Francisco.     D.  Gutmann, 
manager. 

Veritas  {Bode  or  Fellowcraft)  Mine. — At  San  Andreas.  Since  the  last 
report,  an  inclined  shaft  (at  an   angle  of  about  55  degrees)  has  been 


106 


CALIFORNIA    STATE   MINING    BUREAU. 


sunk  200  feet  on  a  vein  cutting  through  mica  schist.  At  the  100-foot 
level  a  cross-cut  has  been  run  east  to  a  zone  of  amphibolite  schist  and 
quartz,  4  to  8  feet  wide.  On  the  200-foot  level  a  cross-cut  has  been 
extended  135  feet  east  of  the  shaft  to  this  vein,  which  is  there  8  feet 
wide.  The  mine  is  equipped  with  a  10-stamp  steam  mill  and  water  hoist, 
but  is  idle.  On  the  hill,  back  of  the  shaft,  is  a  zone  of  mineralized  quartz 
schists,  which  prospects  in  gold,  and  is  apparently  the  most  promising 
part  of  the  property,  but  nothing  has  been  done  with  it  in  the  way  of 

development. Veritas  Gold  Mining  Company,  owners.     F.  J.  Solinsky 

of  San  Andreas,  agent. 

Commodore  Mine. — One  mile  north  of  San  Andreas,  on  the  Mother 
Lode.     A  vertical  shaft  has  been  sunk  80  feet,  thence  continuing  at  an 


Cross  Section  showing  succession   of   Pormations    at^ 
(oMMODORfc  A)iN&,  lrTiile.N.of  c>AN-AiNOC{eA&.  CalaVeras  Co.  C-ai_. 

Pig.  31. 

angle  of  75  degrees  to  the  eastward  to  a  depth  of  300  feet.  A  level  had 
been  run  north  250  feet  April  1st,  developing  a  wide  zone  of  mineralized 
rock,  which  in  its  normal  condition  is  quartz  diorite  (No.  21).  This 
occurs  as  a  wedge-shaped  intrusion,  coming  from  the  north.  Serpentine 
forms  both  the  foot  and  hanging  walls  of  this  lode.  To  the  westward, 
on  the  Masterson  claim,  is  a  broad  zone  of  ankerite,  so  frequently  men- 
tioned as  occurring  elsewhere,  with  its  massive  quartz  outcrop  and 
characteristic  mariposite,  and  to  the  eastward  of  the  serpentine  the 
formation  is  a  normal  diabase.  A  cross-section  is  illustrated  in  the 
sketch  (Fig.  31). 

The  Commodore  vein  is  somewhat  of  an  anomaly  in  this  region.  It  is 
a  matter  of  interest  to  know  that  the  quartz  diorite,  the  alteration  and 
mineralization  of  which  form  this  ore-body,  is  almost  identical,  both 
mineralogically   and  in  physical  appearance,  with   a  dike  of  quartz- 


THE    MOTHER    LODE    REGION — CALAVERAS   COUNTY.  107 

diorite  (No.  20)  intruding  the  amphibolite  schist  in  the  Union  Copper 
Mine  at  Copperopolis,  in  this  county.  On  the  hanging-wall  side  of  the 
Commodore  vein  is  a  zone  of  crushed  material,  4  feet  in  width,  in  which 
occur  rhombic  crystals  of  dolomite.  These,  upon  being  fractured,  may 
be  observed  to  contain  visible  particles  of  gold.     The  mine  is  equipped 

with  a  steam  hoist.     There  are  10  men  employed. Commodore  Gold 

Mining  Company  of  Stockton,  owners.  W.  H.  Clarey  of  San  Andreas, 
superintendent. 

Illinois  Mine. — It  is  6  miles  south  of  San  Andreas,  on  the  Copper- 
opolis road,  near  the  Demarest  Mine.  Since  the  last  report  it  has  been 
equipped  with  a  steam  hoist  and  a  10-stamp  mill.  An  inclined  shaft 
has  been  sunk  to  a  depth  of  200  feet,  and  two  levels  opened.  There  are 
two  veins,  one  running  N.  5°  E.,  and  the  other  N.  30°  W.,  converging 
northward.  The  formation  is  clay  slate  on  the  foot-wall,  and  amphib- 
olite schist  on  the  hanging-wall.  A  banded  vein  occurs  at  the  contact 
of  these  formations,  and  a  brecciated  gray  ore  in  the  schistose  portion. 
Idle. B.  K.  Thorn  of  San  Andreas,  owner. 

Demarest  Mine. — This  is  6  miles  south  of  San  Andreas,  near  the  road 
to  Copperopolis.  It  is  an  old  mine,  which  has  been  reopened  since  the 
last  report  was  issued.  An  inclined  shaft  has  been  sunk  to  a  depth  of 
640  feet,  and  still  sinking  in  April,  1900.  It  has  a  steam  hoist  and  a 
5-stamp  mill.  A  short  shoot  of  very  good  rock  has  been  encountered  in 
the  several  levels  of  this  mine,  the  formation  in  which  it  occurs  being 
diabase.  A  gouge  usually  accompanies  the  vein.  This,  in  the  northern 
end  of  the  mine,  lies  on  the  hanging-wall  side  of  the  quartz,  on  the  300- 
foot  level.  Some  distance  south  of  the  shaft  there  is  a  sudden  flexure 
of  the  walls  of  the  vein,  the  gouge  passing  over  to  the  foot-wall  side  of  the 
quartz.  A  second  shoot  of  what  is  said  to  be  good  ore  is  known  to  exist 
under  the  bed  of  the  creek  south  of  the  main  workings,  but  this  has  not 

as  yet  been  reached  under  ground.     There  are  18  men  employed.- The 

Demarest  Gold  Mining  Company  of  Angels,  owners.  T.  H.  Fullen  of 
Altaville,  superintendent. 

The  Ford  Mine. — It  is  three  fourths  of  a  mile  east  of  the  Mother  Lode, 
at  San  Andreas.  The  rock  formation  is  chiefly  chlorite  schist,  resulting 
from  the  alteration  of  diorite  and  possibly  also  diabase.  The  foot-wall 
(west)  of  the  mineral  belt  of  the  Ford  Mine  is  a  hard,  dense,  quartz 
schist,  often  impregnated  with  iron  sulphide  (pyrite),  which  is  usually 
auriferous,  though  at  this  place  to  a  limited  extent.  The  hanging-wall 
country  is  greenstone  schist,  not  materially  different  from  that  exposed 
in  the  mine  workings.  There  are  two  other  rocks  in  the  mine  which  lie 
near  the  foot-wall.  These  are,  first,  a  hard,  tough,  dark-green  rock 
(No.  23),  composed  of  an  aggregate  of  talc  scales,  often  schistose,  and  in 
an  extreme  state  of  alteration  passes  over  to  talc  schist  and  massive 


108  CALIFORNIA   STATE   MINING    BUREAU. 

steatite;  second,  a  dolomitic  rock  (magnesian  limestone),  which  is  also 
much  altered  and  passes  over  to  talc  schist.*  This  rock  greatly 
resembles  the  ankerite  of  the  Gold  Belt,  but  shows  no  green  mariposite. 
These  two  rocks  are  of  structural  importance  only,  as  no  ore  has  as  yet 
been  found  in  them.  The  Ford  Mine  may  be  described  as  a  mineral 
belt  consisting  chiefly  of  chloritic  and  talcose  schists,  lying  upon  a  quartz 
schist  foot-wall,  and  having  a  hanging-wall  of  diorite,  locally  found 
altered  into  chlorite  schist.  The  included  belt  is  about  100  feet  in  width, 
and  within  it  occurs  large  lens-like  masses  of  quartz,  and  also  vein-like 
sheets  of  quartz.  The  former  are  often  found  mixed  with  a  gray  rock 
which  is  a  portion  of  the  greenstone.  These  masses  of  quartz  and  frag- 
mentary greenstone  are  a  common  feature  of  many  important  mines  of 
the  California  Gold  Belt,  and  often  constitute  large  and  valuable 
deposits  of  gold  ore;  but  there  are  many  millions  of  tons  of  rock 
seemingly  identical,  which  are  of  little  or  no  commercial  value,  owing 
to  the  extremely  low  tenor  in  gold.  In  the  Ford  Mine,  as  elsewhere, 
these  large  deposits  contain  a  variable  percentage  of  iron  sulphide 
(pyrite).  The  large  quartz  bodies  range  from  a  foot  or  two  to  nearly 
100  feet  in  width.  There  is  a  small  vein  near  the  foot-wall  side  which 
appears  to  possess  elements  of  value,  but  to  what  extent  it  is  impossible 
to  say.  This  vein  has  a  strike  west  of  north,  dipping  easterly  with  the 
main  quartz  bodies,  but  not  connected  with  them  down  to  the  400-foot 
level.  This  vein  and  the  small  feeders  of  quartz  running  into  it  have 
produced  rock  of  phenomenal  richness.  It  also  contains  considerable 
quantities  of  petzite  (gold-lead-silver-bearing  tellurium).  The  gold  and 
tellurium  occur,  in  this  small  vein  and  the  stringers  leading  into  it,  in 
Avhat  is  known  as  an  ore-shoot — that  is,  the  distribution  of  the  gold  in 
the  vein  appears  to  be  chiefly  confined  to  a  limited  area,  apparently  30 
or  40  feet  in  length,  and  having  a  trend  along  the  vein  downward  to  the 
north  at  about  35  degrees  from  the  horizontal.  Gold  has  been  found 
nowhere  else  in  this  vein  than  along  the  shoot  as  described.  A  persistent 
characteristic  of  this  vein  is  the  occurrence  of  thin  films  of  iron  sulphide 
incrusting  the  cracks  and  seams  of  the  quartz.  In  this  vein  gold  was 
found  on  the  surface;  south  of  the  shaft  on  and  above  the  100-foot 
level;  in  the  shaft  at  about  the  100- foot  level;  in  a  winze  sunk  on  this 
level  north  of  the  shaft;  and  in  a  drift  north  of  the  shaft  on  the  300- 
foot  level,  Avhere,  I  am  informed,  a  $900  pocket  was  found.  The  repeated 
occurrence  of  the  gold  and  tellurium  at  the  points  indicated,  shows 
clearly  the  downward  and  northward  trend  of  the  ore-shoot.  The  mine 
is  equipped  with  a  steam  hoist  and  10-stamp  mill.  The  mine  is 
developed  to  a  depth  of  700  feet,  and  I  am  informed  that  the  shaft  is  to 

*An  investigation  of  similar  rocks,  near  Forest  Hill,  Placer  County,  has  led  me  to 
believe  that  the  two  rocks  here  described  represent  different  stages  in  the  alteration  of 
the  same  rock. 


THE  MOTHER  LODE  REGION CALAVERAS  COUNTY.  109 

be  sunk  200  feet  more.     There  are  10  men  employed. Ford  Mining 

Company   of   San    Andreas,    owners.     D.    Gutmann    of    San  Andreas, 
manager. 

Angels  Mine. — Is  in  the  town  of  Angels,  and  is  the  second  mine  north 
of  the  Utica,  and  presumably  on  the  same  vein.  It  comprises  a  group 
of  five  fractional  claims.  The  mine  was  worked  extensively  in  former 
years,  but  until  a  year  or  more  since  has  remained  idle  for  many  years. 
A  vertical  shaft  has  been  sunk  350  feet,  and  three  levels  opened  on  a 
zone  of  amphibolite  schist  and  quartz  containing  gold  and  auriferous 
iron  sulphide.  Only  the  north  end  of  the  property  is  in  operation.  The 
ore  is  crushed  in  a  custom  mill.     The  mine  is  equipped  with  a  steam 

hoist.     There  are  40  men  employed;  24  in  the  mine, Angels  Quartz 

Mining  Company  of  San  Francisco,  owners.     0.  S.  Buckbee  of  Angels, 
superintendent. 

Lightner  Mine. — In  the  town  of  Angels,  the  first  extension  north  of 
the  Utica,  and  on  the  same  vein.  The  Lightner  is  a  fractional  claim, 
on  which  a  shaft  has  been  sunk  to  a  depth  of  447  feet,  and  five  levels 
opened.  The  vein  consists  of  a  zone  of  amphibolite  schist  and  quartz, 
ranging  from  10  to  90  feet  in  width,  and  is  essentially  the  same  as  the 
Utica  Mine,  geologically.  The  gray,  granular  dike  rock,  characteristic 
of  the  Utica-Stickle  Mine,  which  forms  large  masses  of  the  best  ore  of 
that  property,  is  also  prominent  in  the  Lightner.  The  mine  is  sub- 
stantially timbered  with  a  modification  of  the  square-set  system.  The 
property  has  a  good  hoisting  plant,  air-compressors,  electric  machinery, 
and  a  40-stamp  mill.     The  mill  is  operated  by  electricity,  the  hoist  by 

steam.     There  are   50   men  employed. The  Lightner  Gold  Mining 

Company  of  Stockton,  owners.     V.  W.' Miller  of  Angels,  superintendent. 

The  Lightner  Mill. — This  is  a  modern  mill  of  40  stamps,  run  under 
the  direction  of  J.  E.  Reaves.  It  originally  contained  20  stamps,  but 
was  enlarged  to  40.  Twenty  of  the  stamps  weigh,  when  new,  955 
pounds,  and  twenty  weigh  750  pounds.  The  height  of  drop  of  the 
heavier  stamps  is  7  inches;  that  of  the  lighter,  7^  inches.  The  number 
of  drops  is  about  100  per  minute;  the  height  of  discharge,  8^  to  9 
inches.  A  No.  1  punched  tin  screen  is  used.  The  capacity  under  these 
conditions  is  about  5  tons  per  stamp  daily  (by  car  measurement).  This 
tonnage  is  probably  due  to  the  peculiar  character  of  the  ore,  which  con- 
sists of  a  considerable  quantity  of  chloritic  schist  and  calcite,  and  sharp 
grains  of  quartz,  which  pulverize  readily,  the  stamp  cutting  the  softer 
material  rapidly.  The  gold  is  mostly  caught  inside  the  battery.  The 
apron  plates  are  24  by  48  inches;  the  sluice  plates  are  divided  and  are 
20  inches  by  20  feet.  No  traps  of  any  kind  are  in  use.  There  are  20 
Frue  vanners — twelve  4-foot  and  eight  6- foot  machines.  The  ore  con- 
tains about  2  per  cent  of  pyrite.     The  pulp  from  the  batteries  is  divided, 


110 


CALIFORNIA    STATE   MINING   BUREAU. 


but  not  sized,  before  going  to  the  vanners.  The  speed  of  the  concen- 
trating machines  is  controlled  by  means  of  a  cone  pulley.  An  experi- 
ment was  made  on  a  lower  discharge  (at  7^  incbes),  which  resulted  in 
scouring  of  the  inside  plates.     This   was  discontinued  for  the  higher 

PocKEtT  in   ^\ILL  c>CREE:N 

LiGHTNEtR  M.ill, 

Angels,  California. 


P  =  PocKc+T  W. '    Iron  Wedges. 

Fig.  32. 


discharges  now  in  use.  Chrome  shoes  and  white  iron  dies  are  in  use  in 
this  mill.  The  latter  last  five  months,  crushing  750  tons  of  ore.  The 
concentrates  at  this  mill  are  worked  by  chlorination  at  the  Utica  plant. 
An  ingenious  screen  has  been  invented  by  Mr.  Reaves,  which  is  illus- 
trated in  the  accompanying  sketch  (Fig.  32). 
The  screen  is  fitted  with  two  pockets  at  the 
front,  and  these  may  be  opened  at  will,  and 
chips  or  other  foreign  matter  removed  by 
inserting  the  hand.  The  method  of  securing 
the  screen  to  the  frame  is  shown  in  the  illus- 
tration. (Fig.  33  is  an 
Chuck  Block  illustration  of  the  Lightner 
chuck-block,  with  iron  rods 
to  protect  the  plate  from 
scouring.) 

Utica- Stickle  Mine. — It  is 
at  Angels.  Since  the  last  report,  a  vertical 
shaft  has  been  sunk  to  a  depth  of  1370  feet. 
This  shaft  is  located  south  and  east  of  the  old 
shafts,  and  is  in  the  hanging- wall  schists.  It 
is  substantially  timbered  throughout  with  heavy  sets,  and  a  large,  expen- 
sive hoisting  plant  has  been  installed.  This  machinery  sets  on  concrete 
foundations,  which  were  constructed  in  the  most  substantial  manner. 
For  more  than  a  year  the  lower  levels  have  been  flooded  in  the  southern 


Ljc^htn&rMill. 
R.R.  Iro^f^cds. 


Fig.  33. 


THE  MOTHER  LODE  REGION — CALAVERAS  COUNTY.         Ill 

part  of  the  property.  When  the  new  vertical  shaft  was  completed  it 
was  found  that  the  hoisting  plant,  with  the  use  of  which  the  shaft  had 
been  sunk,  was  incapable  of  doing  more  than  handle  the  water  coming 
in  at  that  point,  and  it  was  determined  to  discontinue  mining  operations 
in  the  lowest  levels  until  such  time  as  it  became  possible  to  put  in  a 
heavy   plant  that  would  economically  handle  both  the  water  and  ore. 

Theorder  for  the  newmachinery  was  promptly  placed, and  it  should  have 
been  in  position  in  August,  1899,  but  owing  to  the  inability  of  the  makers, 
the  Union  Iron  Works  of  San  Francisco,  to  furnish  necessary  material, 
due  to  scarcity  of  iron,  the  great  hoist  was  not  ready  for  operation  until 
early  in  September,  1900.  During  the  past  year  or  more  all  mining 
operations  in  this  property  have  been  confined  to  the  upper  levels  of  the 
mine. 

The  lower  levels  will  now  be  unwatered  and  the  large  new  ore-bodies 
discovered  prior  to  the  flooding  of  this  portion  of  the  mine  will  be  worked 
vigorously.  This  property  also  includes  the  Madison  and  Gold  Cliflf 
mines,  situated  half  a  mile  west  of  the  Utica-Stickle  group. 

An  extensive  electric  installation  has  been  added  to  the  Utica  Com- 
pany's plant.  The  generators  are  located  above  Murphys,  on  the  com- 
pany's ditch-line.  The  power  is  distributed  to  their  various  properties  at 
Angels,  where  they  also  sell  power  and  light  the  town.  The  Utica- 
Stickle  and  Gold  Cliff  mills  are  operated  by  this  power,  and  also  the 
mill  of  the  Lightner  Company,  adjoining  the  Utica. 

Gold  Cliff  Mine. — This  is  one  of  the  Utica  group,  and  is  being  opera- 
ted through  an  inclined  shaft  600  feet  deep,  sunk  from  the  level  of  the 
old  open  cut.  Four  levels  have  been  opened  in  this  mine.  The  vein 
is  found  in  a  broad  zone  of  amphibolite  schist,  with  serpentine  on  the 
hanging-wall.  The  ore  occurs  in  several  zones,  which  overlap  in  the 
foot-wall  going  north.  On  the  400-foot  level  north  of  the  shaft,  the  vein 
splits,  being  separated  by  a  horse  of  diabase.  Whether  or  not  these 
diverging  veins  will  re-unite  is  not  known.  The  ore  from  the  Gold  Cliff 
Mine  is  crushed  in  the  40-stamp  Madison  mill.  At  the  Utica  Mine  there 
is  a  60-stamp  mill,  and  the  Stickle  also  has  a  60-stamp  mill,  making  a 
total  of  160  stamps  on  the  consolidated  properties.  There  are  420  men 
employed  in  and  about  these  works,  distributed  as  follows:  Utica,  125; 
Stickle,  90;    Gold   Cliff,  40;    the  mills,  25;  chlorination  and  cyanide 

plant,  30;  outside,  110. Hayward,  Lane,  and  Hobart  Estate  of  San 

Francisco,  owners.  J.  L.  Shinn,  manager.  The  Madison  Mine  has  been 
idle  for  some  time. 

Utica  Mills. — The  three  Utica  mills  are  under  the  superintendence  of 
W.  J.  Loring.  The  stamps  of  the  Utica  mills  weigh  780  pounds;  those 
of  the  Stickle,  835  pounds;  and  of  the  Madison,  920  pounds.  These 
drop  from  7  to  8  inches  105  to  107  times  a  minute.     The  height  of  dis- 


112  CALIFORNIA   STATE   MINING   BUREAU. 

charge  in  the  Utica  mill  is  10  inches;  Stickle  mill,  7  inches;  Madison,  5 
inches.  The  Utica  and  Stickle  mills  are  provided  with  No.  1  punched 
tin  screens,  and  the  Madison  with  No.  2.  The  capacity  of  these  several 
mills  will  average  about  5  tons  per  stamp  daily.  With  the  heavier 
stamps  and  low  discharge  of  the  Madison  mill,  it  would  be  expected  that 
the  capacity  of  that  mill  would  exceed  that  of  the  Utica  or  Stickle,  but 
the  Gold  Cliff  rock  is  much  harder  than  that  of  the  other  mines. 

Mr.  Loring  gives  the  following  description  of  the  Utica  60-stamp  mill, 
and  the  daily  routine  work,  together  with  method  of  making  monthly 
clean-up,  etc.: 

The  rock,  as  hoisted  from  the  mines,  is  dumped  at  the  head  of  the 
shaft  over  a  grizzly  made  of  3-inch  round  iron  bars,  10  feet  long,  placed 
1|  inches  apart,  and  set  at  an  inclination  of  40  degrees.  The  bars  are 
supported  at  each  end  by  an  iron  casting,  with  recesses  to  receive  them. 
Old  stamp  stems  are  used  in  the  grizzly.  At  the  lower  end  of  the  grizzly 
the  rock  passes  to  a  Blake  crusher  10  x  16  inches,  being  fed  by  gravity. 
One  crusher  of  this  size  handles  all  the  rock  for  the  60-stamp  mill. 
One  man  is  employed  here  on  each  ten-hour  shift. 

The  crusher  and  grizzly  set  over  a  50-ton  bin,  from  which  ore  is  con- 
veyed to  three  bins  of  200  tons  capacity  each  in  the  mill  by  means  of 
a  dump  car.  The  bins  discharge  into  Challenge  feeders.  In  the  Utica 
mill  they  have  made  a  practice  of  keeping  on  hand  a  new  cam  shaft 
with  ten  cams  in  place,  which,  in  event  of  breaking  the  shaft,  may  at 
once  take  the  place  of  the  broken  shaft.  In  case  of  such  difficulty, 
much  time  is  saved  by  this  arrangement.  The  discharge  in  the  batteries 
is  10  inches  high;  three  differential  chuck-blocks  are  in  use,  keeping 
the  discharge  as  nearly  uniform  as  possible.  Manganese  steel  shoes  are 
used;  these  are  10  inches  long,  8^  inches  in  diameter  of  face,  and  weigh, 
new  177  pounds;  when  worn  out,  they  weigh  but  28  pounds;  their  life 
is  about  296  days.  The  dies  are  made  of  hard  iron,  and  last  120  days; 
they  are  5  inches  high,  8|  inches  in  diameter  of  face,  and  9^  x  9^ 
inches  base  area;  they  weigh  84  pounds,  and  after  using,  about  one  half 
of  this.  Round  needle  punched  tin  screens  are  used  in  sheets  10  x  14 
inches;  No.  1,  or  30-mesh,  has  been  found  to  give  the  best  satisfaction, 
and  lasts  from  15  to  20  days.  Before  using,  these  are  burned  over  a 
moderate  fire  of  charcoal,  for  the  purpose  of  removing  the  tin,  to  pre- 
vent amalgamation  of  the  tin.  This  anneals  the  metal,  and  makes  it  a 
very  tough,  durable  screen.  A  splashboard  made  of  1  x  12  inch  clear 
pine,  having  the  full  width  of  the  screen,  is  suspended  to  the  screen 
frame  by  two  eyestraps  riveted  to  each  end  of  the  board  and  two  hooks 
screwed  to  the  screen  frame.  A  strip  of  canvas  6  inches  wide  is  tacked 
to  the  lower  end  of  the  board,  to  confine  the  splash  to  the  apron. 
Underneath  the  screen  is  bolted  an  iron  apron,  which  constitutes  a  por- 
tion of  the  mortar,   and  being  an   inch  below  the  lip  of  the  mortar. 


Ill  .  ! 


North  Shaft  and  Mii.i.,  Utica  Mine,  Calaveras  County. 


■  The  Keystone  Mine  and  Mill,  Amador  City. 


THE    MOTHER    LODE    REGION — CALAVERAS   COUNTY.  113 

permits  the  insertion  of  a  rough  board  1x12  inches,  which  lies  flush 
with  the  upper  edge  of  the  lip  of  the  mortar.  Upon  this  the  pulp  from 
the  screen  falls,  and  it  is  considered  a  good  amalgamator.  After  being 
in  use  a  short  time,  it  amalgamates  quickly,  but  does  not  stand  the  jar 
as  well  as  the  copper  plate.  A  splashboard  of  this  kind  can  be  cleaned 
in  one  eighth  of  the  time  required  to  clean  a  copper  plate.  The  board 
is  protected  by  a  2x6  inch  board,  extending  across  the  apron,  and 
having  a  |-inch  hole  bored  at  each  end  to  receive  two  hooks  fastened  to 
the  battery  posts.  Four  inches  below  the  board,  on  the  apron,  runs  a 
trough  in  which  are  two  apertures  3  inches  square,  through  which  the 
pulp  passes  to  a  copper  plate  5  inches  wide,  with  a  pitch  toward  the 
mortar,  whence  it  passes  to  the  sluice  plates,  2  feet  wide  and  22  feet 
long,  covered  with  yg-i^^ch  copper  plates  set  on  a  grade  of  2  inches  to 
the  foot.  Each  battery  has  two  separate  runs  of  these  plates,  set  inde- 
pendently, provided  with  wedges  to  adjust  the  grade.  Before  putting 
on  the  plates,  the  tables  are  dressed  down  in  the  center  about  j-^  inch 
for  the  full  length.  This  causes  the  pulp  to  run  in  angular  waves 
across  the  plate.  If  the  tables  are  left  plain  without  the  center  depres- 
sion, it  is  a  difficult  matter  to  cause  the  pulp  to  be  evenly  distributed 
over  the  plate,  as  it  usually  flows  to  one  side  or  the  other.  The  first 
8  feet  of  plate  at  the  upper  end  of  each  sluice  is  raw  copper,  the  remain- 
ing 14  feet  being  plated  with  2^  ounces  of  silver  to  the  square  foot. 
The  plating  is  done  in  the  works  of  the  company.  The  plates  are 
cleaned  every  morning. 

A  plug  of  soft  wood  is  driven  into  one  of  the  3-inch  holes  of  the  cast- 
iron  aprons  previously  described,  causing  the  pulp  to  run  through  the 
trough  and  out  of  the  other  3-inch  hole  discharging  on  the  other  plate. 
The  plate  to  be  dressed  is  first  washed  with  clean  water  to  remove  sand 
then  sprinkled  with  quicksilver,  and  rubbed  vigorously  with  a  whisk- 
broom  for  the  purpose  of  loosening  the  amalgam.  About  once  a  week 
a  weak  solution  of  cyanide  of  potassium  is  used  in  dressing  the  plate. 
This  operation  must  be  done  with  care,  as  the  application  of  too  much 
cyanide  causes  the  plates  to  become  glazed  and  brittle,  when  they  are 
no  longer  fit  for  the  use  for  which  they  are  intended.  After  the  plates 
have  been  thoroughly  rubbed  with  a  whisk- broom,  they  are  rubbed  down- 
ward with  a  piece  of  pure  India  rubber  -|  inch  thick,  4  by  7  inches  in 
area.  The  amalgam  is  then  taken  up,  together  with  the  sulphides  which 
may  have  adhered  to  the  plates  during  the  twenty-four  hours.  The 
plate  is  then  lightly  sprinkled  with  quicksilver  at  the  head,  and  lightly 
brushed  with  a  whisk-broom  its  full  length.  The  last  plate  is  always 
brushed  upward  from  the  lower  end,  to  place  any  amalgam  which  should 
be  hanging  to  the  lower  edge  of  the  plate  in  a  position  where  it  may  be 
seen  and  collected.     By  this  method,  two  men  can  dress  twenty-four 

8 — MB 


114  CALIFORNIA   STATE   MINING   BUREAU. 

sluices,  22  feet  in  length  by  2  feet  wide,  in  from  one  and  a  half  to 
two  hours. 

For  the  purpose  of  saving  the  rich  sulphurets  which  have  adhered  to 
the  plates,  and  which  are  often  worth  $10  per  pound,  the  amalgam  col- 
lected each  morning  is  cleaned  in  a  tank  used  for  that  purpose  only. 
At  the  end  of  the  month  this  tank  is  cleaned  out  and  the  sulphurets 
are  charged  with  25  pounds  of  quicksilver,  into  an  amalgamating  barrel 
of  40  inches  diameter  and  48  inches  long.  This  revolves  for  eight 
hours,  at  14  revolutions  per  minute.  The  charge  is  taken  out  through 
the  head  with  a  dipper,  is  panned  and  settled.  The  amalgam  is  cleaned 
in  the  usual  way,  and  the  sulphurets  sent  to  the  chlorination  works  in 
a  wooden  bucket.  At  the  lower  end  of  the  sluices  is  a  tail-box,  having 
the  width  of  a  double  sluice,  with  a  drop  of  3^  inches,  and  a  width  of  5 
inches  on  the  bottom.  This  box  has  a  wing  its  full  length,  with  a  pitch  of 
about  45  degrees  toward  the  sluice  plates,  and  extends  to  within  ^  inch 
of  the  bottom  of  the  box.  The  wing  causes  the  pulp  to  pass  under  it 
and  keep  the  box  clear  at  the  bottom,  catching  any  free  quicksilver. 
From  this  opening  extends  a  sluice  12  inches  wide  and  8  feet  long,  the 
upper  end  of  which  is  provided  with  ^  x  ^  inch  riffles  2  inches  apart, 
while  below  the  riffles  are  6  feet  of  silver-plated  copper  plates.  This 
box  has  a  grade  of  |  inch  to  the  foot,  and  from  it  the  tailings  pass  to  the 
concentrators. 

Each  battery  has  three  concentrators.  There  are  in  use  in  the  several 
mills  of  the  company  fifty-four  4-foot  Frue,  six  4-foot  Union,  and  six- 
teen 3  foot  10  inches  TuUoch  machines.  A  series  of  comparative  tests 
was  made  some  time  since,  which  showed  little  difference  in  the  value 
of  the  tailings  passing  the  machines.  Mr.  Loring  made  special  experi- 
ment with  several  of  the  Frue  machines.  The  machine  has  a  shaking- 
frame  12  feet  long  and  4  feet  wide.  The  back  roller  was  dropped  3 
inches  by  putting  a  block  of  wood  between  the  side  rail  and  the  bearing 
that  supports  the  roller.  Then  a  number  of  small  rollers  which  carry 
the  belt  were  taken  out,  reducing  the  total  length  of  the  concentrator  to 
8  feet  from  the  center  of  the  head  roller  to  the  center  of  the  small  roller. 
The  belt  from  the  small  roller  to  the  back  roller  had  so  much  grade  that 
nothing  was  saved  on  it,  so  that  by  this  arrangement  of  the  concentra- 
tors the  effect  was  the  same  as  though  the  machines  were  but  8  feet  long. 
Tailings  assays  showed  as  follows: 

From  the  altered  machine,  4x8  feet $0  33  per  ton. 

From  the  unaltered  machine,  4x12  feet.. -_. 41  per  ton. 

This  shows  a  saving  of  8  cents  per  ton  in  favor  of  the  short  concen- 
trator. This  being  the  case,  it  would  appear  that  a  12-foot  machine  is 
unnecessarily  long.  On  each  concentrator  is  a  discharge,  which  deposits 
the  sulphurets  in  a  box  directly  under  the  head  roller  of  the  machine, 
and  from  this  box  the  concentrated  sulphurets  are  removed  daily.     A 


THE    MOTHER   LODE   REGION — CALAVERAS   COUNTY.  115 

car  holding  900  pounds  is  used  to  convey  'them  to  the  dump-house. 
Two  samples  are  taken  from  each  car  with  a  15-inch  sampling  iron, 
and  after  all  concentrates  for  the  day  have  been  taken  out  and  sampled, 
the  aggregate  sample  is  sent  to  the  assay  office,  together  with  the  aggre- 
gate of  the  samples  of  tailings,  taken  every  three  hours.  These  samples 
are  assayed  every  day,  and  a  record  kept.  The  tailings  from  the  con- 
centrator run  through  a  flume  three  fourths  of  a  mile  long,  and  are 
passed  over  a  slimes  plant  of  the  Gates  type.  The  concentrates  from 
the  slimes  plant  are  conveyed  by  wagon  to  the  chlorination  works, 
wliere  they  are  worked  in  a  cyanide  plant  attached  to  that  department 
of  the  works. 

After  a  run  of  fifteen  or  twenty  days,  depending  on  the  character  of 
the  ore,  a  general  clean-up  of  the  mills  is  made,  as  follows:  The  feed 
is  shut  off  from  three  batteries  until  they  have  been  "pounded  out"; 
the  stamps  are  then  hung  up,  the  water  shut  off,  and  two  rectangular 
pans,  16x14  inches  in  area,  3  inches  deep  on  one  side  and  2  inches  on 
the  other,  are  placed  in  front  of  each  battery,  the  low  side  of  each  being 
slipped  under  one  of  the  holes  in  the  apron.  These  pans  are  made  in  this 
form  to  keep  the  upper  edge  as  nearly  level  as  possible  when  sitting  on 
an  inclined  plane.  The  amalgam  adhering  to  the  screen  frame  is  taken 
off  with  a  scraper,  and  deposited  in  a  gold-pan.  The  screen  frame  is 
then  removed  and  washed;  afterwards  the  chuck-block  is  taken  out  and 
placed  in  the  clean-up  room,  to  be  cleaned;  the  wooden  apron  is  then- 
scraped  and  the  amalgam  put  into  a  bucket;  the  coarse  battery  sands  are 
then  shoveled  into  a  box  provided  for  that  purpose,  and  the  pans  with 
the  cleanings  from  the  screen  frame  are  successively  put  under  each 
stamp,  which  is  thoroughly  cleaned  of  any  amalgam  found  in  key-ways 
or  between  the  boss-head  and  shoe.  After  each  stamp  has  been  thor- 
oughly cleaned  in  this  way,  the  amalgam  is  taken  to  the  clean-up  room, 
a  check  being  kept  on  the  weight  of  that  from  each  battery  separately. 
The  dies  are  then  removed  and  washed  on  the  apron,  and  the  batteries 
cleaned  out,  all  the  hard  sand  that  has  accumulated  around  the  dies 
being  put  in  an  amalgamating  barrel.  After  the  mortar  has  been 
thoroughly  cleaned,  about  half  an  inch  of  sand  is  spread  on  the  bottom 
of  the  mortar,  the  dies  are  returned  to  their  respective  places,  coarse 
sand  packed  in,  and  the  chuck-block,  which  has  been  cleaned,  replaced; 
the  screen  is  replaced  and  keyed;  the  apron  washed,  and  everything 
cleaned,  down  to  the  rectangular  pans  previously  mentioned.  These 
pans,  and  the  buckets  used  around  the  battery,  are  washed  into  the 
amalgamating  barrel.  By  the  time  the  clean-up  man  has  completed 
washing  the  buckets  and  pans,  the  man  employed  In  looking  after  the 
self-feeders  has  started  the  cleaned-up  battery,  and  has  its  neighbor 
ready  to  be  opened.  Three  men  on  the  batteries  and  three  men  in  the 
clean-up  room  can  clean  up  twelve  batteries  in  three  hours.     When  the 


116  CALIFORNIA    STATE    MINING    BUREAU., 

battery  is  first  hung  up,  the  small  spreader  plates  are  taken  to  the 
clean-up  room,  and  the  amalgam  obtained  is  dropped  into  a  tank, 
which,  after  the  clean-up,  is  cleaned  out  and  charged  with  other  material 
in  the  amalgamating  barrel. 

After  the  mill  has  been  cleaned  up,  150  pounds  of  quicksilver  is  put 
into  the  barrel,  with  sufficient  water  to  give  a  depth  of  12  inches  over 
the  charge.  The  barrel  is  then  closed,  locked  and  sealed,  and  the  belt 
put  on,  which  drives  the  barrel  at  14  revolutions  per  minute.  This 
charge  is  run  30  to  48  hours.  Underneath  the  barrel  is  a  tank  of  equal 
capacity,  from  whence  a  sluice  22  feet  long  and  12  inches  wide  with  a 
grade  of  1|  inches  to  the  foot,  provided  with  silvered  copper  plates,  con- 
veys the  pulp  and  water  to  either  of  two  settling  tanks  as  desired. 
When  the  barrel  has  run  its  full  time,  it  is  stopped  with  the  head  up, 
the  head  removed,  and  a  stream  of  clear  water  under  high  pressure 
turned  in,  causing  the  slimes  to  come  to  the  top  of  the  barrel,  overflow, 
and  fall  into  the  tank  beneath,  from  which  they  pass  through  the  sluice 
into  a  tank  of  2000  gallons  capacity.  When  the  slimes  have  been 
washed  out,  the  water  is  shut  off.  A  bucket  is  set  under  the  If-inch 
plug-hole  in  the  barrel,  and  the  charge  is  drawn.  The  quicksilver  first 
flows  out,  falling  to  the  bottom  of  the  bucket.  A  stream  of  water  is 
kept  running  through  the  barrel  to  wash  the  sand  through  the  discharge 
hole,  and  the  bucket  is  thoroughly  scraped,  so  that  the  sand  will  over- 
flow, leaving  the  amalgam  in  the  bottom,  the  "iron"  next,  and  the  sand 
on  top.  The  iron  is  taken  out  as  it  accumulates,  and  after  it  has  all 
been  collected,  it  is  screened  through  a  ^-inch  screen  and  the  screenings 
panned  in  the  clean-up  tank.  The  result  is  put  back  into  the  amalga- 
mating barrel  at  the  next  regular  clean-up.  The  amalgam  from  the  barrel 
is  thoroughly  cleaned  and  squeezed  through  white  drilling.  The 
amalgam  balls  weigh  from  8  to  12  pounds,  and  retort  about  38  per  cent 
gold.  The  day  before  the  buckets  are  to  be  cleaned,  the  accumulations 
on  the  sluice  plates  are  scraped  ofi"  with  steel  scrapers  made  of  old  files 
turned  at  one  end  about  2  inches,  and  ground  to  a  sharp  edge.  The  first 
8  feet  of  raw  plate  is  scraped  in  this  way,  leaving  the  14  feet  of  silvered 
plate  to  run  six  months  more  without  scraping.  Great  care  must  be 
taken  in  scraping  silvered  plates,  as  the  silver  cuts  easily,  spoiling  the 
plate  and  making  low-grade  bullion.  The  amalgam  thus  collected  is 
put  in  a  small  amalgamating  barrel  15  inches  in  diameter  and  24 
inches  long,  which  is  run  28  revolutions  a  minute,  quicksilver  being 
added,  with  enough  water  to  make  a  thin  paste  of  the  charge.  The 
charge  is  run  for  twenty-four  hours,  when  it  is  drawn  off  in  a  bucket  and 
cleaned  in  the  usual  way,  the  sulphurets  being  saved  in  the  cleaning 
tank  previously  described.  This  amalgam  yields  from  28  to  30  per  cent 
gold. 

Quicksilver   is   fed   to   the   battery  every  hour;    the    amount    being 


THE    MOTHER    LODE    REGION — CALAVERAS    COUNTY.  117 

regulated  by  the  value  of  the  ore,  and  this  must  be  judged  by  the  amal- 
gamator from  examination  of  the  board  directly  under  the  splash  of  the 
battery,  where  the  pulp  first  falls  from  the  screen.  Every  ounce  of 
quicksilver  that  is  fed  into  the  battery  is  weighed  and  recorded  at  the 
end  of  each  shift,  and  at  the  end  of  the  run  the  amount  of  quicksilver 
thus  fed  furnishes  a  basis  for  calculating  the  probable  result  of  the 
clean-up  before  it  is  made.  The  retorts  are  lined  with  oak  wood  ashes, 
free  from  dirt;  the  ashes  are  sifted  through  a  30-mesh  screen,  and  made 
into  a  paste  Avith  water;  with  this  paste,  the  trays  and  retorts  are  lined, 
and  the  head  thickly  sealed.  The  ashes  do  not  shrink  like  clay,  to 
which  it  is  superior  in  many  ways. 

The  mortars  in  the  Utica  mill  are  of  an  old-fashioned  type,  not 
having  been  provided  with  liners.  After  being  in  use  several  years,  it 
was  found  necessary  to  do  something  if  the  life  of  the  mortars  was  to  be 
prolonged,  as  the  ends  were  badly  worn  just  above  the  dies  The  stamps 
were  set  10  inches  between  centers,  using  8^-inch  shoes,  leaving  a  space 
of  1^  inches  between  each  two  shoes.  The  9-inch  dies  up  to  that 
time  had  a  life  of  59  days,  and  the  chrome  steel  shoes  were  being  used 
191  days.  In  order  to  line  these  mortars,  Mr.  Loring  reset  the  stamps, 
using  a  guide  with  9^  inches  between  centers,  and  leaving  |  inch  between 
stamps.  In  this  manner  1^  inches  were  gained  at  each  end  of  the 
mortars,  allowing  room  for  an  end  liner,  which  served  to  key  the  front 
and  back  liners.  The  back  was  filled  with  wood,  carefully  fitted  in 
place  with  the  liner,  saving  considerable  Aveight  of  unnecessary  iron. 
The  back  liner  is  13  inches  high,  and  stands  at  an  angle  of  11\  degrees, 
the  foot  being  1\  inches  from  the  base  of  the  die.  These  dies  are  made 
with  8|-inch  face,  while  the  shoes  have  but  S^-inch  face.  It  is  claimed 
by  Mr.  Loring  to  give  better  results  than  when  both  shoe  and  die  are  of 
the  same  diameter. 

The  chuck-blocks  are  made  of  wood  covered  with  copper,  I  inch  thick 
and  8  inches  wide,  the  full  length  of  the  battery.  In  the  center  the 
copper  is  bent  to  fit  the  wooden  block,  the  upper  half  being  set  at  an 
angle  of  45  degrees,  the  lower  half  standing  vertically.  At  the  lower 
edge  of  the  block,  and  projecting  ^  inch  over  the  copper,  is  bolted  a  ^  x  1 
inch  iron  strap  the  full  length  of  the  copper.  At  the  bend  in  the  copper^ 
or  about  2  inches  above  the  bottom  iron,  is  bolted  a  second  iron  strap, 
"I  X I  inch,  the  full  length.  The  bolts  holding  these  iron  straps  are 
countersunk,  and  the  iron  bars  act  as  a  protection  for  the  amalgam 
which  accumulates  between  them,  and  it  has  also  been  found  to  prevent 
the  scouring  of  the  upper  section  of  the  plate.  There  are  used  8^ 
gallons  of  water  per  battery  of  5  stamps  per  minute,  and  in  addition 
2i  gallons  per  minute  outside  for  each  battery. 

All  chips,  shoe  wedges,  and  other  wood  used  about  the  mill,  are 
saved  and  burned  in  a  5  X  8-foot  furnace  constructed  for  that  purpose. 


118  CALIFORNIA   STATE   MINING    BUEEAU. 

The  furnace  has  a  cement  floor;  above  it  are  placed  grate  bars  to  the 
full  size  of  the  furnace.  The  furnace  measures  from  cement  floor  to  top 
of  bars,  15  inches;  from  the  top  of  bars  to  the  top  of  the  arch,  5  feet; 
at  the  top  of  the  furnace  is  a  charging  hopper  made  of  cast-iron,  with 
a  door  to  fit  it.  When  the  charge  has  been  burned,  the  ashes  are 
removed  and  screened  to  remove  nails,  etc.,  that  may  be  in  the  charge. 
The  ashes  are  put  in  the  amalgamating  barrel  with  10  pounds  of  quick- 
silver, and  ground  for  six  hours  sharp,  as  a  longer  time  would  probably 
cause  the  charge  to  "flour."  From  6  ounces  to  2  pounds  of  amalgam  is 
obtained  by  this  method  every  month.  All  the  cleanings  from  the  mill 
are  put  into  this  barrel  and  ground  for  such  time  as  the  case  may 
require.  In  this  way  many  thousands  of  dollars  are  saved  around  a 
large  plant,  by  care.  The  amalgam  from  the  chuck-blocks  is  ground  in 
an  iron  mortar  12  inches  in  diameter,  the  muller  of  which  has  a  con- 
nection made  in  such  a  way  that  it  can  be  stopped  or  lifted  as  desired. 
It  will  grind  a  charge  of  14  pounds,  and  has  a  speed  of  65  revolutions 
per  minute.  The  labor  employed  in  the  mill  is  as  follows:  One  man  to 
each  shift  of  twelve  hours,  whose  duty  it  is  to  look  after  the  feeding  of 
the  batteries;  one  night  amalgamator,  who  attends  to  the  amalgamating 
and  looks  after  the  mill  generally;  one  concentrator  man  on  each  twelve- 
hour  shift,  who  attends  to  36  concentrators;  one  day  amalgamator  and 
helper,  who  attend  to  the  amalgamating  and  general  repairs  about  the 
mill;  one  superintendent,  who  has  charge  of  everything  connected  with 
the  mills  and  plating  works;  thus  seven  men,  besides  the  superintendent, 
operate  a  60-8tamp  mill.  Owing  to  the  fact  that  the  company  own  their 
power,  against  which  they  make  no  charge  for  the  plant  or  deterioration, 
the  cost  of  milling  at  the  Utica  mills  is  very  low,  being,  before  the  recent 

rise  in  the  price  of  iron,  about   14   cents  per  ton. W.  J.  Loring, 

superintendent,  Utica  Mills. 

The  Utica  Chlorination  Works. — This  plant  consists  of  seven  furnaces, 
having  a  daily  capacity  of  29  tons.  F.  C.  Beedle  is  superintendent. 
Four  of  the  furnaces  are  in  constant  operation.  They  are  72  x  13  feet, 
and  have  a  capacity  of  4|  tons  each  daily.  The  material  treated  in  these 
furnaces  is  iron  sulphide,  concentrated  from  the  Utica-Stickle  and  Gold 
Cliff  ores.  The  tanks  are  made  of  redwood  held  by  |-inch  round  iron 
rods,  each  in  three  sections  and  secured  with  screw  clamps.  This 
method  of  clamping  tanks  draws  the  staves  evenly,  secures  great  firm- 
ness, and  renders  the  tanks  perfectly  water-tight.  The  covers  of  the 
tanks  are  no  longer  "luted"  on  as  formerly,  but  are  provided  with  a 
downwardly  projecting  flange,  which  drops  in  an  annular  trough 
encircling  the  tank  and  filled  with  water.  The  accompanying  diagram 
(Fig.  34)  illustrates  this  construction  of  the  air-tight  water  joint.  The 
covers  are  raised  by  means  of  a  chain  block  suspended  from  an  over- 
head traveler.     The  tanks  have  a  capacity  of  5  tons  each.    .  The  pipes 


THE    MOTHER    LODE    REGION — CALAVERAS   COUNTY. 


119 


from  the  chlorine  gas  generators,  which  latter  are  very  large,  are  so 
arranged  that  when  the  gas  is  turned  into  No.  1  tank,  having  permeated 
the  ore  below,  it  passes  from  the  top  of  No.  1  tank  into  the  bottom  of 
No.  2,  so  that  there  is  no  waste  of  gas.  In  generating  gas,  100  pounds 
of  salt  and  90  pounds  of  black  oxide  of  manganese  are  used.  To  this,  * 
sulphuric  acid  is  automatically  added,  until  it  ceases  to  evolve  gas. 
Liquid  chlorine  was  at  one  time  tried  in  these  works,  but  Mr.  Beedle 
said  it  was  found  to  cost  twice  as  much  as  making  gas  by  the  above 
described  method,  though  otherwise  satisfactory.  The  ore  is  introduced 
to  the  reverberatory  furnaces  containing  5  to  10  per  cent  moisture,  in  a 
charge  of  2600  pounds.     It  is  spread  in   a  2-inch  layer  on  the  first 


Explanation. 

5.    S-Taves  forming  vat. 

O.    Outside  ring,  encircling  vat. 

W.    Space  filled  wifb  water. 

Ft    Plan§e  extending  downward  from 
cover. 


H. 
P. 


Iron  Hoop. 
Pilling  piece. 


Section    of    Cover  and  1op  of  Vat,  Ch?lorination  Works, 
UTICA   MiNE.;ANG£LS,  Cal. 
showing     air-tt^ht     w^ater     joint.  — 
Fig.  34. 

hearth.  After  two  hours  it  is  stirred,  and  later  it  is  restirred  three 
times  before  being  raked  forward  to  the  second  hearth.  On  the  second 
hearth,  40  pounds  of  salt  are  added  to  the  charge;  on  the  third  hearth, 
the  ore,  having  been  thoroughly  roasted,  is  withdrawn  from  the  furnace, 
cooled  and  charged  into  leaching-vats.  One  and  one-quarter  cords  of 
wood  are  required  to  roast  5  tons  of  ore. 

Utica  Cyanide  Plant.— In  this  plant  8800  pounds  of  slimes  obtained 
from  the  canvas  plant  are  treated  in  eight  hours.  This  is  charged  in 
steel  tanks,  and  agitated  6  hours  with  a  5  per  cent  solution  of  potassium 
cyanide.  The  pulp  is  discharged  into  a  vacuum  filter,  and  is  first 
washed  with  sump  solution,  and  later  with  fresh  water.  The  results 
are  said  to  be  entirely  satisfactory.  The  auro-cyanides  are  precipitated 
on  zinc  shavings. 

Bovee  Mine. — This  property  adjoins  the  Fox  or  Angels  Mine  on  the 

north,  at  Angels.     It  has  been  idle  for  many  years. The  Marshall 

Mining  Company,  owners.     E.  P.  Lynch  of  Angels,  agent. 


120  CALIFORNIA   STATE   MINING   BUREAU. 

Perlina  Mine. — At  Altaville,  northeast  of  the  Angels  Mine.  It  has 
an  inclined  shaft  75  feet  deep,  from  which  drifts  have  been  run  on  the 
vein.  The  property  has  been  superficially  worked  for  years,  the  ore 
being  crushed  in  a  4-stamp  mill.  The  vein  has  never  been  cross-cut, 
and  its  width  is  unknown.  As  far  as  known  at  this  writing,  the  vein 
has  a  width  of  from  4  to  12  feet,  between  two  gouge  seams.  The 
formation  is  diabase  and  amphibolite  schist.  There  are  3  men  em- 
ployed.  J.  G.  Maltman  of  Angels,  owner. 

Great  Western  Mine. — At  Altaville.  It  has  a  vertical  shaft  220  feet 
deep,  with  drifts  at  50,  100,  and  200  feet  south  of  the  shaft,  no  work  of 
consequence  having  been  done  to  the  northward.  There  is  a  stope  at 
the  50  foot  level  and  one  at  the  100-foot  level.  On  the  latter  level,  it  is 
said  the  vein  is  from  8  to  20  feet  in  width.     The  hoisting  machinery  has 

been  removed  and  the  mine  is  idle. Seifert  &  Baumhogger  of  Angels, 

owners. 

St.  Lawrence  Mine  (Bruner  or  Bald  Hill). — This  mine  has  been 
reopened  since  the  last  report,  and  an  inclined  shaft  sunk  400  feet  at 
an  angle  of  64  degrees;  there  is  a  level  at  100  feet  and  another  at  400 
feet.  An  open  cut  on  the  surface  exposes  a  shoot  of  ore  80  feet  in  length, 
which  was  worked  down  to  a  depth  of  60  feet  many  years  ago.  The 
trend  of  this  shoot  is  to  the  south,  at  an  angle  of  40  degrees;  two  other 
shoots  are  known  to  the  northward.  The  formation  is  diabase  and 
chlorite  schist.  The  vein  consists  of  a  mixture  of  quartz  and  diabase, 
impregnated  with  auriferous  iron  sulphides  and  free  gold.  The  mine  is 
equipped  with  a  steam  hoist,  but  has  no  mill.  The  south  drift  at  the 
400-foot  level  had  not  renched  the  ore-shoot  at  the  time  of  my  visit,  but 

drifting  was  in  progress. St.  Lawrence  Gold  Mining  Company  of 

Hanford,  Cal.,  owners.     A.  J.  Cameron  of  Angels,  superintendent. 

Bolytho  Mine. — This  is  1  mile  south  of  Angels,  and  has  been  men- 
tioned in  previous  reports.  It  was  originally  worked  as  a  pocket  mine, 
and  as  such  produced  several  thousand  dollars  in  gold.  Expensive 
development  was  then  undertaken,  with  a  view  to  working  it  as  a 
milling  proposition,  but  up  to  this  time  the  experience  of  the  operators 
has  been  rather  unsatisfactory.  The  last  work  performed  was  the  sink- 
ing of  a  vertical  shaft  to  a  depth  of  300  feet;  this  shaft  passed  through 
a  succession  of  formations — diabase  tuft"  and  tufaceous  slate,  character- 
istic of  the  Gold  Belt,  being  most  prominent.  These  formations  are 
intruded  by  a  dike  of  straw-colored  rock,  which  is  identical  with  the 
intrusive  rock  found  in  the  Utica-Stickle,  Gold  Cliff,  and  other  important 
mines  in  this  section.  The  dike  is  from  30  to  40  feet  wide,  and  carries 
much  finely  disseminated  iron  sulphide,  which  is  doubtless  auriferous, 
but  to  what  extent  is  not  known  by  the  management,  as  no  attention 
was  paid  to  it,  for  the  reason  that  it  was  not  massive  quartz.     It  is  the 


THE    MOTHER    LODE    REGION — CALAVERAS   COUNTY.  121 

intention  of  the  company  to  cross-cut  from  the  bottom  of  the  shaft  to 
the  eastward  and  again  intersect  the  dike,  which  is,  undoubtedly,  what- 
ever its  value  may  be,  the  main  ore  zone  of  the  mine.  When  this  is 
done,  long  drifts  will  be  run  for  the  purpose  of  prospecting.  Geolog- 
ically, this  mine  possesses  many  of  the  features  common  to  the  best 
mines  of  this  section.  In  addition  to  this  shaft,  an  inclined  shaft  has 
been  sunk  300  feet  on  a  west  vein,  and  thousands  of  feet  of  drifting  and 
cross-cutting  have  been  done  in  the  upper  portions  of  the  mine  in  search 
of  pockets  and  pay  rock.  The  vertical  shaft  is  equipped  with  a  steam 
hoist. Bolytho  Mining  Company,  Appraiser's  Building,  San  Fran- 
cisco, owners.     E.  P.  Lynch  of  Angels,  superintendent. 

Big  Bonanza  Mine  (Harris  or  Oriole).— It  is  1  mile  south  of  Angels, 
and  has  been  developed  by  a  vertical  shaft,  which  was  425  feet  in  depth 
May  1,  1900.  A  level  has  been  run  at  130  feet,  60  feet  southeast,  and 
another  at  200  feet.  The  formation  in  which  this  mine  occurs  is  augite 
diorite,  in  which  occur  fine-grained  phenocrysts  of  hornblende  and 
augite.  This  rock  near  the  vein  is  altered  to  chlorite  schist.  The  vein 
consists  of  a  zone  of  quartz  and  schistose  rock,  dipping  75  to  80  degrees 
to  the  eastward.  The  mine  is  equipped  with  a  substantial  steam  hoist, 
but  has  no  mill.  There  are  15  men  employed.  Sinking  is  in  progress. 
It  has  been  recently  reported  that  30  feet  of  ore  has  been  developed  on 
the  400-foot  level,  5  feet  of  which  is  high  grade. Oriole  Mining  Com- 
pany of  Stockton,  owners.     John  H.  Heard  of  Angels,  superintendent, 

Drake  Properties  (Ltd.). — These  are  a  mile  southeast  of  Angels.  Two 
shafts  have  been  sunk— one  900  feet,  the  other  300  feet— vertically  for 
the  purpose  of  prospecting.  The  formation  is  diabase  and  black 
tufaceous  slate,  the  latter  being  cut  by  a  small  dike  with  quartz  and 

pyrite.     Idle.- ^Drake  Properties   (Ltd.)  of   London,  owners,    F,   J. 

Solinsky  of  San  Andreas,  agent. 

Tulloch  Mine.— It  is  2h  miles  south  of  Angels,  After  a  long  idleness 
it  has  been  reopened  and  sinking  is  in  progress  in  the  shaft,  which  Sep- 
tember 1st  was  down  250  feet.  Steam  hoist.  There  are  12  men 
employed. Mr.  Blevin  of  Angels,  superintendent. 

Relief  Mine.— It  is  1  mile  south  of  Angels.  It  has  a  cross-cut  tunnel 
165  feet  long,  and  a  winze  sunk  on  a  zone  of  schist  90  feet  below  the 

tunnel  level.     The  mine  has  no  machinery.     Idle. Bonded  to  San 

Francisco  company.     Mr.  Hogarth  of  Angels,  owner. 

Melones  Consolidated  Mines. — This  group  of  mines  is  on  Carson  Hill, 
reaching  frohi  the  summit  of  that  eminence  to  the  Stanislaus  River, 
and  embraces  seven  claims  extending  along  the  lode  for  a  distance  of  a 
mile.  The  claims  are  the  Reserve,  Last  Chance,  Melones,  Enterprise, 
Mineral  Mountain,  Keystone,  and  Stanislaus.  These  mines  were  among 
the   first  worked   in    the   county,  and   the   several   claims   have   been 


122  CALIFORNIA   STATE   MINING   BUREAU. 

developed  to  depths  varying  from  superficial,  though  large  cuts,  to 
shafts  300  feet  or  thereabouts  in  depth.  The  development  undertaken 
by  the  present  owners  consists  in  an  extension  of  the  South  Carolina 
tunnel.  (This  property  adjoins  the  Melones  Consolidated  on  the  east.) 
It  was  run  through  the  Enterprise  and  Reserve  ground  under  the  large 
open  cuts  on  the  surface,  and  connection  established.  It  is  621  feet 
below  the  collar  of  the  Reserve  shaft.  This  development  has  exposed 
large  veins  of  ankerite  and  quartz  with  amphibolite  schist,  all  of  which 
is  gold-bearing,  with  auriferous  sulphides.  To  what  extent  these  great 
veins  are  auriferous  is  of  course  a  very  important  factor,  viewed  from 
the  commercial  standpoint.  The  values  vary  greatly,  ranging  from 
many  thousands  of  dollars  per  ton  to  a  mere  trace  of  gold.  Large 
samples  taken  systematically  from  cross-cuts  on  the  veins  show  values 
varying  from  $1.50  to  about  $9,  the  greater  portion  running  from  .$2.50 
to  $3.50  per  ton,  though  some  portions  average  better  than  this,  accord- 
ing to  statements  made  by  the  management.  A  new  tunnel  (designated 
as  No.  3),  6  feet  6  inches  by  9  feet  clear,  was  started  to  run  under  the 
South  Carolina  tunnel  about  200  feet  lower.  This  tunnel  is  now  in  about 
3500  feet,  and  judging  from  the  character  of  the  formation  passed  through 
in  the  last  100  feet  is  nearing  the  vein.  The  tunnel  cuts  diagonally 
across  the  formation,  and  is  being  driven  through  the  foot-wall  country- 
It  is  perfectly  straight,  has  a  double  track  throughout,  and.  is  a  credit- 
able piece  of  mine  engineering.  Machine  drills  are  in  use,  the  com- 
pressors being  situated  near  the  mouth  of  the  tunnel.  There  are  still 
several  hundred  feet  to  run  before  this  tunnel  reaches  a  point  beneath  a 
winze  sunk  from  the  South  Carolina  tunnel.  A  raise  of  65  feet  from 
the  new  tunnel  will  make  this  connection  at  a  point  1000  feet  below  the 
cropping  on  the  summit  of  Carson  Hill.  The  grade  for  a  i20-stamp 
mill  has  been  completed,  and  a  large  amount  of  machinery  is  on  the 
mill  site.  The  first  attempt  to  construct  a  dam  across  the  Stanislaus 
for  the  purpose  of  furnishing  power  for  this  property  was  a  failure,  and 
a  new  site  was  chosen  a  few  feet  higher  up  the  stream.  This  is  about  2| 
miles  above  Robinson's  Ferry.  The  dam  is  being  put  in  at  this  writing 
(September  1,  1900),  and  it  is  stated  that  no  obstacles  to  its  successful 
construction  have  been  encountered  thus  far.  The  water  diverted  by  the 
dam  will  be  conducted  by  ditch  and  flume  to  a  point  opposite  the  mill 
site,  and  it  is  calculated  to  furnish  power  for  the  entire  plant.  This  is 
one  of  the  largest  mining  operations  in  the  State,  but  much  still  remains 

to  be  done  before  it  can  be  placed  on  an  operating  basis. Melones 

Consolidated  Mining  Company  of  Boston,  owners.     W.  C.  Ralston  of 
Robinson's  Ferry,  manager. 

Last  Chance  Mine. — Near  the  town  of  Angels,  on  the  southern  limits. 
Nothing  has  been  done  here  since  the  last  report.  It  has  an  inclined 
shaft  73  feet  in  depth. G.  C.  Tryon  of  Angels,  owner. 


THE  MOTHER  LODE  REGION CALAVERAS  COUNTY.  123 

San  Justo  {Carson  Creek)  Mine. — The  work  in  progress  May  1,  1900, 
is  in  a  south  drift  on  the  250-foot  level,  where  a  new  ore-shoot  has  been 
discovered.  The  mill,  which  had  long  been  idle,  was  started  up  May 
1st,  and  the  chlorination  works  one   month  later.     The  mill  has  40 

stamps;  40  men  are  employed. The  San  Justo  Mining  Company, 

Parrott  Building,   San  Francisco,   owners.     V.   W.    Miller  of   Angels, 
superintendent. 

Greek  Mine. — Near  the  road  between  El  Dorado  and  Railroad  Flat,  20 
miles  from  San  Andreas.  It  is  developed  by  a  shaft  170  feet  deep,  with 
a  drift  120  feet  long  at  the  100-foot  level.  The  vein  cuts  vertically 
through  mica  schist,  and  has  the  remarkable  accompaniment  of  two 
dikes — the  older  a  dark-green,  hard  diorite;  the  later,  a  light-colored, 
finely  grained  dike  of  acid  type.  The  latter  is  usually  found  in  contact 
with  the  vein,  which  is  either  banded  or  massive,  showing  in  places 
coarse  gold.  The  general  tenor  of  the  ore,  however,  is  low  grade.  It  is 
equipped  with  a  steam  hoist  and  a  5-stamp  mill.  Idle. Greek  Min- 
ing Company  of  San  Andreas,  owners.  F.  J.  Solinsky  of  San  Andreas, 
agent. 

Bitter  Mine. — This  is  1^  miles  north  of  Mountain  Ranch,  or  El  Dorado. 
It  is  opened  by  a  tunnel  410  feet  in  length,  driven  on  a  small  vein  of 
granular  quartz  having  a  peculiar  schistose  structure.  The  rock  is 
extremely  hard  and  flinty.  One  shoot  of  ore  developed  by  this  tunnel 
and  a  raise  produced  considerable  high-grade  specimen  rock.  The  vein 
strikes  N.  30°  W.,  and  is  intersected  by  a  larger  quartz  vein,  striking 
north  and  south  and  dipping  65  degrees  east.  This  vein  is  dislocated 
by  the  smaller  vein  a  distance  of  40  feet.     A  small  force  was  at  work 

in  the  spring  of  1900. Rodesino  Estate  of  Mountain  Ranch,  owners. 

Bonded  to  S.  Redmond  of  San  Andreas. 

Blue  Jay  and  Yellow  Hammer  Mines. — These  mines  are  2^  miles  east 
of  Mokelumne  Hill,  near  the  Calaveras  River,  and  comprise  3100  feet 
on  a  banded  vein  in  Calaveras  formation.  The  vein  is  from  2  to  6  feet 
wide,  cutting  mica  schist  and  slate.     It  is  usually  accompanied  by  a 

small    acid    dike.      The   property   is    in  the   prospective    stage. F. 

Courtmarsh  et  al.  of  Mokelumne  Hill,  owners. 

Esperanza  Mine. — It  is  2i  miles  northeast  of  Mokelumne  Hill.  Devel- 
oped by  an  inclined  shaft  1000  feet  deep.  The  property  is  equipped  with 
hoisting  works,  30-stamp  mill,  and  chlorination  plant  of  three  furnaces; 
motive  power,  water.     Idle  in  the  spring  of  1900,  but  it  was  said  that 

I  the  mine  was  about  to  resume  operations. Esperanza  Mining  Com- 

:  pany,  220  Sansome  Street,  San  Francisco,  owners.     Prescott   Ely  of 
\  Mokelumne  Hill,  superintendent. 

!      Calaveras  Mine. — It  is  2^  miles  north  of  Mokelumne  Hill,  near  Big 
j  Bar  bridge.    It  was  described  in  former  reports  as  the  Garner.     The  vein. 


124  CALIFORNIA    STATE   MINING   BUREAU. 

which  occurs  in  diorite,  is  opened  through  an  adit  tunnel.  A  vertical 
shaft  is  being  sunk  from  the  surface,  calculated  to  reach  the  vein  at 
a  depth  of  350  feet,  and  a  winze  is  being  sunk  below  the  tunnel,  70  feet 
north  of  this  shaft.  The  vein  strikes  N.  of  E.,  dipping  W.  57°.  The 
ore  is  crushed  in  a  10-stamp  mill,  situated  on  the  opposite  side  of  the 
Mokelumne  River,  in  Amador  County,  power  being  furnished  by  a  tur- 
bine wheel,  using  about  1200  inches  of  water.  The  mill  runs  during  the 
day  only.  At  the  mill  an  air-compressor  furnishes  power  for  drills  used 
in  the  mine  on  the  other  side  of  the  river.     There  are  24  men  employed. 

Calaveras  Gold  Mining  Company,  owners.      Peter   Houghton   of 

Mokelumne  Hill,  superintendent. 

North  Star  Drift  Mine. — This  is  2  miles  south  of  Mokelumne  Hill,  on 
the  Old  Woman's  Gulch  blue  lead.  The  channel  has  been  reached  by 
means  of  a  cross-cut  tunnel,  in  1360  feet  March,  1900.  This  tunnel 
is  6^  X  10^  feet.  Nine  men  are  employed,  there  being  as  yet  no  machin- 
ery.  North  Star  Mining  Company,  owners.  P.  Schuman  of  Mokel- 
umne Hill,  superintendent. 

Ellen  Vannan  Drift  Mine. — This  is  half  a  mile  below  the  North  Star 
Mine  in  Old  Woman's  Gulch,  and  on  the  same  channel.     It  is  opened 

through  an  inclined  shaft  195  feet  deep.     Six  men  are  employed. W. 

J.  Jackson  et  al.  of  San  Andreas,  owners. 

Green  Mountain  Mine  (Hydraulic  and  Drift). — This  mine  was  being 
operated  by  hydraulic  process  with  success  during  the  spring  of  1900, 
under  permit  of  the  United  States  Debris  Commission,  employing  12 
men  during  the  day  only.  From  a  portion  of  this  claim  there  have 
been  shipped,  within  the  past  two  years,  12  tons  of  quartz  crystals,  for 
which  this  mine  has  long  been  famous.  These  were  placed  with  Tiffany 
&  Co.  of  New  York,  who  estimated  their  value  at  about  $18,000. 
Several  handsome  and  absolutely  perfect  crystal  spheres  have  been 
cut  from  the  crystals  obtained  in  this  mine,  but  the  limit  of  the  size  of 
a  perfect  sphere  has  thus  far  been  about  5^  inches.  A  statement  was 
made  to  the  writer  by  one  of  the  owners,  that  Mr.  Tiffany  had  said  that 
if  a  crystal  could  be  obtained  which  would  cut  a  sphere  7  inches  in 
diameter,  which  should  prove  to  be  absolutely  faultless  and  without  a 

flaw,  such  a  sphere  would  have  a  valuation  of  $30,000. J.  E.  Burton 

et  al.,  owners.     J.  McSorley  of  Mokelumne  Hill,  superintendent. 

Emery  Hydraulic  Mine. — Also  known  as  the  Rose  Hill.  One  mile 
from  Mountain  Ranch.  This  mine  is  situated  on  a  branch  of  the  Fort 
Mountain  channel.  It  was  being  operated  in  the  spring  of  1900  with 
800  inches  of  water,  and  two  monitors  working  twenty-four  hours  daily, 
two  pits  having  been  opened.  No  work  was  in  progress  in  the  south 
pit.  The  work  in  the  north  pit  is  being  carried  down  stream,  a  long 
tunnel  having  been  cut  for  drainage.     The  water  pressure  at  the  upper 


THE    MOTHER   LODE    EEGION — CALAVERAS   COUNTY.  125 

pit  was  300  feet,  at  the  lower  pit  400  feet.  The  company  owns  2^  miles 
on  the  line  of  this  channel.  The  bank  has  averaged  thus  far  about  20 
feet  in  height.  From  2000  to  2500  yards  are  moved  every  twenty-four 
hours,  when  a  full  head  of  water  is  available.  The  owners  have  spent 
a  large  sum  of  money  in  perfecting  their  water-system,  consisting  of 
reservoirs,  ditches,  pipe-lines,  etc.     In  the  mine  10  men  are  emiDloyed; 

15  on  other  work. Emery  Gold  Mining  Company  of  Mountain  Ranch, 

owners.     Earle  C.  Emery  of  Mountain  Ranch,  superintendent. 

San  Domingo  Hydraulic  {Jupiter)  Mine. — This  property  was  being 
worked  in  May,  1900,  with  two  giants  using  1500  inches  of  water  under 
150  feet  head.  The  average  of  the  season  is  estimated  to  be  1.25  yards 
per  day  per  inch  of  water  employed.  The  bank  is  nearly  100  feet  high; 
the  gravel  is  loose,  and  disintegrates  rapidly  under  the  powerful  streams 
from  the  giants.  The  flume  at  this  mine  is  4  feet  in  width,  3000  feet 
long,  and  set  on  a  4-inch  grade.     The    company  owns  about  2  miles 

on  the  channel.     There  are  8  men  employed. The  San  Domingo  Gold 

Mining  Company,  Parrott  Building,  San  Francisco,  owners.  A.  B. 
Thompson  of  Angels,  superintendent. 

■  French  Hill  Quartz  Mine. — This  is  a  prospect  situated  on  the  slope 
of  the  famous  French  Hill,  about  half  a  mile  east  of  Mokelumne  Hill. 
A  cross-cut  tunnel  is  being  driven,  which  in  March  was  in  400  feet. 

There  are  5  men  employed. J.  E.  Burton  et  al.,  owners.     T.  E.  Mc- 

Sorley  of  Mokelumne  Hill,  superintendent. 

■  Satellite  Copper  Mine. — This  property  is  near  Campo  Seco.  When 
visited  in  the  spring,  the  inclined  shaft  was  down  250  feet,  and  sinking. 
The  hoisting  is  being  done  by  means  of  a  gasoline  engine,  which  appears 
to  give  satisfaction.  At  this  mine  an  80-ton  water-jacket  furnace  was 
found  in  full  blast,  operated  by  what  is  known  as  "partial  pyritic 
smelting,"  under  the  direction  of  E.  J.  Fowler,  metallurgical  engineer. 
The  furnace  is  of  special  design,  constructed  from  plans  made  by  Mr. 
Fowler,  in  which  80  tons  of  material  are  treated  daily,  of  which  50  tons 
are  ore,  the  remainder  being  flux.  The  charge  consists  of  raw  ore, 
roasted  ore,  slag,  limestone,  and  low-grade  matte.  In  what  proportion 
these  are  charged  was  not  learned.  Mr.  Fowler  says  that  this  method 
of  pyritic  smelting  is  entirely  feasible  and  successful  on  ores  of  this 
class.  The  ores  are  chalcopyrite  and  pyrite.  A  little  zinc  is  occasion- 
ally seen.  The  ore  contains  but  little  silica,  and  quartz  is  brought  from 
the  croppings  of  neighboring  veins  for  flux. The  Pennsylvania  Man- 
ufacturing Company  of  Campo  Seco,  owners.  A.  C.  Harmon  of  Campo 
Seco,  superintendent. 

Borger  Copper  Mine. — Near  Campo  Seco,  and  in  the  principal  mineral- 
ized zone  of  the  district.  A  new  shaft  is  being  sunk  on  a  promising 
copper  vein  by  Mr.  C.  Borger  of  Campo  Seco. C.  Borger,  owner. 


126  CALIFORNIA   STATE   MINING   BUREAU. 

Union  and  Keystone  Copper  Mines. — They  are  at  Copperopolis,  and 
comprise  a  mile  of  locations  on  the  copper  belt.  The  mines  were  worked 
extensively  in  former  years,  and  produced  a  large  amount  of  copper. 
The  principal  workings  are  down  to  a  depth  of  800  feet.  The  mines 
were  closed  down  in  1893,  and  have  since  remained  idle.  They  were 
unwatered  in  March,  1900,  but  further  than  this  active  operations  have 

not  been  resumed. Union  Copper  Mining  Company  of  Boston,  Mass., 

owners.     G.  McM.  Ross  of  Copperopolis,  superintendent. 

Lightner  Mine. — This  is  2  miles  southeast  of  Copperopolis.  It  has  a 
strong  iron  gossan,  which  occurs  in  amphibolite  schist.  It  is  developed 
by  several  adit  tunnels  and  shallow  shafts.  The  ore  in  the  oxidized 
zone  is  essentially  gold-bearing,  but  being  in  the  copper  belt  it  is  antici- 
pated that  in  greater  depth  in  the  sulphide  zone  more  or  less  copper 

sulphide  will  be  found.     The  mine  has  no  machinery. Mr.  Uren  of 

Alameda,  Cal.,  owner.     Mr.  Lillian  of  Copperopolis,  superintendent. 

Royal  Consolidated  Gold  Mine. — This  is  in  Salt  Spring  Valley  at 
Hodson,  3  miles  northwest  of  Copperopolis.  Since  the  last  report  this 
property  has  been  extensively  developed  under  new  management.  The 
former  operators  worked  a  vein  which  dij^ped  to  the  eastward  at  a  low 
angle,  and  confined  themselves  to  the  defined  limits  of  the  walls  of  that 
vein.  The  quartz  occurred  in  a  series  of  large  lenses  in  a  dike  of  dia- 
base. There  are  a  number  of  nearly  vertical  transverse  veins  which 
come  down  frorft  the  hanging-wall,  intersecting  the  flat  vein  and  passing 
into  the  foot-wall,  but,  strange  to  say,  no  attention  was  given  these 
steeply  inclined  veins  by  the  former  management.  The  present  man- 
agement, however,  undertook  the  exploration  of  the  mine  upon  broader 
lines,  extending  raises  into  the  hanging-wall  and  sinking  winzes  into 
the  foot,  with  the  result  that  large  deposits  of  payable  ore  have  been 
developed  both  above  and  below  the  original  Royal  vein.  In  this  mine 
may  be  seen  some  of  the  largest  stopes  in  the  State.  The  mine  is  almost 
absolutely  dry,  some  of  the  stopes  being  dusty.  Comparatively  little 
timber  is  employed  in  sustaining  the  ground,  and  in  view  of  this  fact 
the  lack  of  substantial  pillars  is  the  cause  of  comment  among  visitors. 
Although  this  ground  is  among  the  best  to  "stand"  of  any  I  have  seen 
in  this  portion  of  the  State,  there  is  a  limit  to  which  this  method  of 
mining  may  be  carried  with  safety.  A  system  of  timbering  and  filling 
must  soon  be  inaugurated  to  avert  disaster,  as  well  as  to  recover  the 
large  ore  reserves  in  sight  in  this  mine.  The  shaft  has  been  sunk  to  900 
feet  from  the  collar,  and  the  lateral  development  is  extensive.  The 
property  is  equipped  with  a  large  steam  hoist  and  a  40-stamp  mill. 

There   are   100   men  employed. Royal  Consolidated  Mines  (Ltd.), 

owner.     J.  C.  Kemp  van  Ee  of  Hodson,  manager. 


f 


THE  MOTHER  LODE  REGION — CALAVERAS  COUNTY.  127 

The  Royal  Mill. — The  mill  of  40  stamps  is  under  the  direction  of  J.  S. 
Shepard.  In  the  old  mill  the  20  stamps  weigh  850  pounds.  In  the 
new  addition  to  the  mill  20  stamps  weigh  1150  pounds  each.  The  old 
stamps  drop  6-5  inches,  and  the  new  5|  inches,  104  times  a  minute.  No.  1 
punched  tin  screens  (24-mesh)  are  used.  The  discharge  is  4  inches 
high,  and  is  maintained  closely  to  this  by  the  use  of  -^-inch  slats  beneath 
the  chuck-block.  The  capacity  of  the  mill  averages  3^  tons  per  stamp 
daily.  The  20  heavy  stamps  of  the  mill  crush  about  14  tons  more  in 
twenty-four  hours  than  the  light  ones.  It  may  be  interesting  to  state 
that  the  capacity  of  this  mill  is  determined  by  weighing  every  car  of  ore 
that  goes  into  the  mill.  There  are  8  Wilflej'',  3  Johnson,  and  1  Frue 
concentrators.  The  pulp  from  the  Wilfley  machines  and  also  that  from 
the  Frue  is  recleaned  on  two  ^yilfley  machines.  The  pulp  from  the 
Johnson  concentrators  is  also  sent  over  the  Wilfley  machines.  This  is  a 
very  unusual  arrangement  of  concentrating  tables,  but  is  stated  to  work 
very  satisfactorily,  producing  clean  concentrates.  At  present  the  sul- 
phides are  sent  to  Selby's  reduction  works.  The  company  has  under 
consideration  the  construction  of  an  additional  60  stamps  and  a  chlor- 
ination  works  at  the  property. 


128  CALIFORNIA    STATE   MINING   BUREAU. 


TUOLUMNE  COUNTY. 


Since  the  last  report  was  issued  by  the  Mining  Bureau  in  1896, 
Tuolumne  County  has  been  the  field  of  unusual  activity  in  mining 
operations.  Encouraged  by  the  success  of  the  Rawhide,  Golden  Gate, 
Black  Oak,  Jumper,  and  other  important  properties  in  this  county, 
many  new  enterprises  were  inaugurated,  and  during  the  years  1897, 1898, 
1899,  Tuolumne  County  was  giving  employment  to  a  large  number  of 
men;  but,  as  has  been  the  case  elsewhere,  some  of  these  investments 
have  thus  far  proven  unremunerative,  and  in  a  few  instances  the  propo- 
sitions have  been  abandoned  permanently,  though  in  other  cases  sus- 
pended operations  will  doubtless  be  resumed.  A  light  rainfall  through 
several  successive  seasons  has  caused  a  shortage  of  water-supply,  which 
has  also  seriously  affected  the  mining  industry  in  this  county,  more  so, 
apparently,  than  in  the  neighboring  counties,  for  at  this  time  mines 
which  have  been  steadily  operating  for  years  are  shut  down  owing  to 
lack  of  water  for  power.  As  an  offset  to  this  unfortunate  condition  is 
the  fact  that  several  of  the  mines  which  have  been  in  process  of  develop- 
ment are  proving  valuable  properties,  and  will  form  welcome  additions 
to  the  list  of  active  producing  mines  of  the  county.  Notable  among 
these  are  the  Eagle-Shawmut  near  Jacksonville,  and  the  Densmore-  near 
Columbia. 

There  is  considerable  activity  in  the  districts  of  smaller  mines  on 
the  East  Lode,  and  reports  of  good  new  properties  in  that  region  may 
be  anticipated.  There  still  remains  a  large  territory  unexplored  in 
Tuolumne  County,  both  on  the  Central  Lode  and  on  the  East  Belt. 
Besides  these  there  are  mines  of  known  merit  in  the  Sierras  which  must  ere 
long  attract  the  attention  of  capital.  Passing  southward  from  Calaveras 
County  into  Tuolumne  at  Robinson's  Ferry,  the  Central  Lode  is  found 
to  continue  in  an  almost  unbroken  line  to  the  southern  boundary  of  the 
county  and  beyond  into  Mariposa.  There  is  a  slight  break  in  its  con- 
tinuity near  Tuttletown,  and  another  break  of  about  1000  feet  between 
Whisky  Hill  and  the  Dutch  Mine,  and  still  another  near  the  foot  of 
Priest's  Hill  on  Moccasin  Creek.  There  may  be  other  interruptions  in 
its  continuity,  but  the  instances  mentioned  are  the  most  noticeable.  In 
fact,  the  lode  is  practically  continuous  through  this  county;  and,  as 
elsewhere,  it  is  characterized  by  its  massiveness  and  distinguished  by 
the  persistent  occurrence  of  massive  quartz  croppings  and  broad  zones 
of  ankerite.  Some  of  the  most  important  mines  on  this  lode  are  found, 
not  in  this  belt  of  ankerite  and  quartz,  but  in  amphibolite  schist  on  the 


THE    MOTHER    LODE    REGION — TUOLUMNE    COUNTY.  129 

hanging-wall  side  of  the  ankerite  zone.  The  Jumper  and  Eagle  mines 
are  notable  examples.  The  East  Lode  in  Tuolumne  County  occurs 
in  the  grano-diorite  and  slates.  An  intermediate  belt  lies  between 
these  two  lodes,  in  which  occur  numerous  pocket  mines  in  greenstone, 
slate,  and  limestone.  Mines  of  this  class  are  prominent  in  the,  vicinity 
of  Sonora  and  near  Big  Oak  Flat. 

Bown  Mine. — This  is  the  first  mine  in  operation  on  the  Central  Lode 
south  of  the  Stanislaus  River.  It  is  half  a  mile  from  Robinson's  Ferry 
and  24  miles  northwest  of  Tuttletown.  A  shaft  had  been  sunk  (June 
27th)  to  a  depth  of  630  feet  at  an  angle  of  64  degrees.  The  vein,  which 
was  being  developed,  is  10  feet  wide  and  lies  underneath  the  ankerite 
zone,  the  foot- wall  being  schist  and  serpentine.  The  vein  has  a  sinuous 
course  and  a  banded  structure,  containing  gold  and  auriferous  pyrite. 
The  shaft  is  in  the  foot- wall,  the  vein  being  reached  by  cross-cuts  from 
the  shaft  at  200,  300,  400,  and  600  foot  levels.  On  the  400-foot  level  a 
cross-cut  has  been  extended  128  feet  beyond  the  vein  into  the  hanging- 
wall.     The  property  is  equipped  with  steam  hoist  and  a  20-stamp  mill, 

in  which  are  8  Union  concentrators.     There  are  20  men  employed. 

Bown  Mining  Company  of  San  Francisco,  owner.  W.  J.  Rule  of  Tuttle- 
town, superintendent. 

Jackass  Hill. — Half  a  mile  south  of  the  Bown  and  east  of  the  anker- 
ite zone  are  the  pocket  mines  of  Jackass  Hill,  the  most  important  of 
which  are  the  Karrington  and  Stenchfield.  This  property  is  worked  by 
several  sets  of  leasers,  who  pay  to  the  owner  a  royalty  on  all  gold  taken 
out.  The  mines  are  reported  to  have  been  regular  and  large  producers 
for  several  years  past.     James  Gillis  of  Sonora,  owner. 

Norwegian  Mine. — It  is  1  mile  north  of  Tuttletown,  overlooking  the 
cafion  of  the  Stanislaus. 

Arhona  Mine. — It  is  at  Tuttletown,  about  i  mile  east  of  the  ankerite 
zone,  in  greenstone  schist.  The  vein  is  from  8  to  10  feet  wide,  and  is 
developed  by  a  shaft  540  feet  deep,  and  sinking  in  June.  A  200-foot 
cross-cut  tunnel  intersects  the  shaft  at  135  feet  from  the  surface.  Levels 
are  run  at  100,  200,  300,  and  400  feet.  The  ore  consists  of  massive  quartz 
and  pyrite.  The  mine  is  equipped  with  steam  hoist  and  10-stamp  water- 
power  mill.  There  are  12  men  employed.  This  mine  was  worked  many 
years  ago  by  French  people,  who  undertook  to  crush  the  rock  in  arras- 
tras,  but  the  quartz  was  found  too  hard  to  crush  readily,  and  it  had 

remained  idle  for  years  when  the  present  owners  renewed  operations. 

Equitable  Mining  and  Milling  Company  of  Stockton,  owners.  W.  E. 
Brooks  of  Tuttletown,  superintendent. 

Rawhide  Mine. — This  property,  3  miles  north  of  Jamestown,  which  for 
several  years  past  had  attracted  much  attention  by  reason  of  its  large 

9 — MB 


130  CALIFORNIA    STATE    MINING    BUREAU. 

and  continued  output,  has  within  the  past  year  been  involved  in  litiga- 
tion among  the  co-owners,  and  when  visited  very  little  information  was 
obtainable,  probably  owing  to  pending  lawsuits.  The  property  was  in 
operation,  however.  Usually  about  100  men  are  employed.  The  surface 
plant  consists  of  a  large  hoist,  a  40-stamp  mill,  and  chlorination  works. 
Ballard,  Martin  &  Nevills  of  San  Francisco,  owners. 

Harvard  (  Whisky  Hill)  Mines. — These  are  a  half  a  mile  west  of  James- 
town, on  the  dolomitic  zone,  though  the  development  of  pay  rock  is 
principally  in  a  zone  of  amphibolite  schist  on  the  hanging-wall  side  of 
the  dolomite.  There  are  two  vertical  shafts — one  of  500  and  one  of  750 
feet  depth.  These  are  connected  by  the  500-foot  level  from  the  south 
shaft.  The  veins  of  pay  rock  consist  of  silicious  amphibolite  schist  of 
variable  width  up  to  35  feet.  The  hanging- wall  is  amphibolite  schist,  hard 
and  firm,  not  gold-bearing,  or  only  slightly  so;  the  foot- wall  is  serpen- 
tine. Hundreds  of  feet  of  levels  have  been  driven  in  the  ankerite  zone, 
but  the  values  are  chiefly  in  the  zone  of  greenstone  schist.  On  the  500- 
foot  level  a  cross-cut  has  been  driven  westward  to  the  massive  quartz 
vein,  probably  the  downward  extension  of  the  "bowlder"  vein  seen  on 
the  surface.  This  cross-cut  develops  nothing  of  value.  The  property  is 
equipped  with  steam  hoists  at  both  shafts,  and  a  60-stamp  mill  which 
is  run  by  electricity.  The  mill  has  both  Johnson  and  Dodd  tables, 
which  effect  a  clean  concentration  of  the  sulphides.  A  series  of  cyanide 
experiments  is  to  be  made,  with  a  view  to  treating  the  sulphurets  by 
that  method.  The  apron  and  sluice  plates  are  6  feet  wide,  divided  by  a 
longitudinal  strip  down  the  center.  The  plates  have  a  grade  of  1^  inches 
to  the  foot.  Thirty  stamps  were  dropping  at  the  time  of  my  visit. 
There  are  two  electric  motors  in  the  mill,  each  of  75  horse-power,  each 

motor  being  calculated  to  run  30  stamps. Harvard  Gold  Mining 

Company,  owners.     J.  P.  Munger  of  Jamestown,  superintendent. 

Dutch  Mine. — It  is  at  Quartz  Mountain,  and  has  been  in  continuous 
operation  since  1893.  The  shaft  has  reached  a  depth  of  1200  feet^ 
inclined  at  58  degrees.  There  are  ten  levels  in  the  mine.  The  develop- 
ment is  chiefly  upon  a  zone  of  ankerite  and  mariposite  60  feet  in 
width,  in  which  are  many  veins  and  lenses  of  quartz,  bearing  gold  and 
auriferous  pyrite,  though  in  greatly  varying  quantities.  The  pay  zone 
is  usually  found  on  or  near  the  foot-wall  side  of  the  ankerite  zone.  The 
foot-wall  country  consists  of  amphibolite  schist,  gabbro,  tufaceous 
slates,  Mariposa  clay  slates,  serpentine,  and  diabase.  These  are  dis- 
tributed somewhat  irregularly.  The  hanging-wall  side  is  principally 
amphibolite  schist,  so  far  as  could  be  observed.  The  pay  shoots  appear 
to  cross  the  ankerite  zone  from  foot  to  hanging  wall  diagonally,  the 
intervening  blocks  of  ground  being  much  lower  in  grade.  There  is  also 
a  noticeable  series  of  slips  in  the  mine,  which  show  that  the  hanging- 
wall  side  of  the  zone  has  in  each  case  been  forced  upward.     These  slips 


THE    MOTHER    LODE    REGION — TUOLUMNE    COUNTY.  131 

like  the  schists  dip  easterly,  but  flatter  than  the  schists.  Northward  on 
the  surface  the  ankerite  extends  for  a  distance  of  1000  feet,  then  disap- 
pears beneath  the  alluvial  of  the  valley,  but  considerable  rock-exposures 
occur  farther  northward,  and  it  is  observed  that  the  ankerite  vein  is  not 
continuous  to  Whisky  Hill.  There  is  an  interval  of  not  less  than  1500 
feet  in  which  it  cannot  be  found,  though  reappearing  on  the  north  side 
of  Woods  Creek  at  the  south  end  of  the  ridge  known  as  Whisky  Hill. 
The  Dutch  Mine  is  equipped  with  a  large  steam  hoist,  the  compressor 
and  mill  of  20  stamps  being  run  by  electricity.  There  are  54  men 
employed.     A  cyanide  plant  was  being  constructed  early  in  July  to 

work  the  sulphides  concentrated  from  the  ores. Dutch  Mining  and 

Milling  Company  of  San  Francisco,  owners.  Albert  Trittenbach  of 
Quartz  Mountain,  superintendent. 

The  App  and  Heslep  Mines. — These  join  the  Dutch  Mine,  and  are 
situated  on  the  northern  end  of  Quartz  Mountain.  The  vein  consists  of 
a  large  mass  of  ankerite  and  quartz,  with  a  black  slate  hanging  and 
diabase  foot-wall.  The  main  shaft  is  down  1000  feet,  equipped  with 
water-power  hoist.  The  mill  has  20  stamps,  and  was  in  operation 
during  midsummer.  There  are  25  men  employed. The  App  Con- 
solidated Mining  Company  of  San  Francisco,  owner. 

Santa  Ysahel  Mines. — These  occupy  the  southern  end  of  Quartz  Moun- 
tain, comprising  several  claims  of  irregular  shape  and  size.  The 
property  was  idle  at  the  time  of  my  visit,  but  it  was  reported  that  opera- 
tions were  to  be  resumed. Santa  Ysabel  Mining  Company  of  Boston, 

owner.     E.  A.  Hardy  of  Quartz  Mountain,  in  charge. 

Jumper  Group  of  Mines. — This  property  is  situated  on  a  low  ridge  half 
a  mile  south  of  the  village  of  Stent,  and  comprises  the  Golden  Rule,  New 
Era,  and  Jumper  mines.  The  Jumper  is  the  principal  mine,  and  is 
being  systematically  worked.  The  Golden  Rule  has  a  large  amount  of 
development,  as  has  also  the  New  Era,  the  latter  chiefly  through  the 
medium  of  levels  extended  into  it  from  the  Jumper.  The  general  struc- 
tural geology  of  the  mine  is  not  wholly  unlike  that  of  other  mines  in 
the  neighborhood.  A  cross-section  taken  in  the  Golden  Rule  in  a  long 
cross-cut  gives  a  good  general  idea  of  the  geological  structure.  Through 
the  entire  length  of  the  hill  the  ankerite  vein  is  prominent,  with  the 
usual  accompaniment  of  large  quartz  lenses;  all  of  this  rock  is  very  low 
grade  in  gold,  however.  The  foot-wall  country  is  diorite,  separated  from 
the  ankerite  zone  by  a  dike  of  serpentine  of  variable  width  (about  100 
feet).  The  ankerite  is  divided  into  two  zones  by  the  intrusion  of  a  large 
dike  of  diorite  similar  to  that  forming  the  west  country.  East  of  the 
ankerite  zone  is  a  succession  of  diorite  and  diabase  dikes,  which  in  part 
are  altered  to  amphibolite  schist,  and  it  is  in  this  schist  that  the  pay 
zone  is  found.     Easterly  from  this  the  formation  is  amphibolite  schist, 


132  CALIFORNIA    STATE    MINING    BUREAU. 

with  dikes  of  granular  diabase.  This  zone  of  schist  is  over  1000  feet 
wide.  In  the  Jumper  Mine  the  gold  occurs  in  a  dike  accompanying  the 
schistose  zone,  and  in  small  veins  and  veinlets  of  quartz  and  calcite, 
scattered  irregularly,  but  always  within  certain  definite  zones,  the  outer 
limits  of  which  form  the  walls.  The  width  of  this  zone  varies  from  4  or 
5  to  about  30  feet.  In  its  earlier  history  an  effort  was  made  to  work  the 
mine  by  selection  of  the  better  from  the  poorer  portions,  but  owing  to  the 
peculiar  geological  conditions  obtaining  the  present  manager  deemed 
this  method  unsuited  to  the  accomplishment  of  the  best  results,  and  the 
method  of  selection  was  abandoned  for  that  of  stoping  everything 
between  the  walls.  This  might  at  first  appear  like  an  extravagant  and 
unnecessary  course  to  pursue,  but  the  results  have  proven  eminently 
satisfactory.  The  .Jumper  is  one  of  the  best  worked  and  best  managed 
mines  in  the  State.  It  is  heavily  and  properly  timbered.  The  walls 
are  hard — that  is,  there  is  no  trouble  from  swelling  ground.  The  main 
shaft  is  down  1285  feet,  and  is  equipped  with  air  and  electricity.  Power 
drills  are  emplo3^ed.  There  are  nine  levels  in  the  mine.  The  mill  has 
60  stamps,  and  has  no  concentrators,  except  one  for  experimental  pur- 
poses.    There  are  125  men  employed. Jumper  Gold  Syndicate  of 

Glasgow,  Scotland,  owners.     M.  D.  Kelly  of  Stent,  superintendent. 

The  Eagle-Shawmut  Mine. — This  property  is  1  mile  north  of  Jackson- 
ville, on  the  ankerite  vein.  Its  distinguishing  feature  is  the  line  of 
massive  quartz  outcrop  which  forms  great,  wall-like  masses  along  the 
course  of  the  vein.  The  hanging-wall  country  is  amphibolite  schist;  the 
foot-wall  is  slate.  The  principal  developments  of  the  mine  consist  of  a 
cross-cut  tunnel  driven  1 100  feet  through  the  foot-wall  country  to  the 
vein,  and  a  shaft  sunk  at  the  tunnel  level  to  a  depth  of  660  feet  on  the 
vein.  The  ankerite  zone  contains  veins  or  lenses  of  quartz,  which  carry 
gold  in  paying  quantities,  besides  which  there  is  a  broad  zone  of  amphib- 
olite schist  on  the  hanging-wall  side,  in  which  is  a  gold-bearing  shoot. 
This  rock  contains  2  or  3  per  cent  of  auriferous  sulphide,  and  is  one  of 
the  most  important  developments  thus  far  made  in  the  mine.  The  super- 
intendent, Mr.  Charles  E.  Uren,  has  introduced  what  appears  to  be  an 
excellent  system  of  stoping  and  filling  in  this  mine.  His  plan  is  to  put 
a  long  raise  to  the  surface  from  a  point  above  the  tunnel  level.  This 
raise  is  driven  at  an  angle  of  about  65  degrees  above  the  horizon,  the 
slope  being  westerly.  The  formation  and  veins  dip  easterly  at  about  70 
degrees.  The  walls  are  usually  firm  and  hard.  The  incline  above  men- 
tioned reaches  the  surface  in  an  open  cut,  where  the  rock  (being  barren ) 
is  suited  for  filling,  and  may  be  quarried  cheaply.  Stopes  are  started 
and  mining  operations  continued  by  cutting  out  the  ground  the  full 
width  of  the  vein  in  the  form  of  the  letter  "A",  the  base  being  longitudi- 
nally of  the  vein  and  the  angle  at  the  apex  being  no  less  than  90  de- 
grees, in  order  that  rock  may  readily  run  on  the  slope.    The  floor  of  this 


THE    MOTHER    LODE    REGION TUOLUMNE   COUNTY.    '  133 

stope  is  heavily  stuUed  and  covered  with  lagging.  The  winze  passes 
directly  through  the  apex  of  this  triangular  stope,  and  waste  is  sent 
down  from  the  surface  and  the  excavation  filled.  Stoping  then  progresses 
in  "slices"  on  alternate  sides  of  the  winze  or  raise.  These  slices  are 
from  15  to  20  feet  in  height,  the  pay  rock  passing  down  through  mill- 
holes  cut  through  from  the  level  below,  the  ore-chutes  being  carried  up 
by  cribbing,  keeping  even  with  stoping  operations,  and  the  filling  run  in 
first  one  side  and  then  the  other,  until  the  block  is  worked  out.  The 
levels  below  are  worked  in  similar  manner,  the  filling  passing  through 
the  stationary  loading  chutes  (at  the  levels)  and  across  the  track  into 
the  next  winze  beneath  by  use  of  an  apron,  which  may  be  removed  when 
desired  until  again  required.  This  method  demands  a  minimum  amount 
of  timbering  and  renders  the  mine  safe  as  far  as  caves  are  concerned. 
It  may  be  elaborated  and  extended  from  level  to  level  and  make  avail- 
able a  large  amount  of  ore  at  low  cost  of  mining.  In  addition  to  the 
ore  deposits  above  referred  to  there  is  upon  the  surface  a  zone  of  amphib- 
olite  schist,  which  contains  a  finely  disseminated  gold.  Experiments 
have  proven  that  this  rock  is  amenable  to  the  cyanide  process.  The  mine 
is  equipped  with  a  40-stamp  mill,  in  which  are  17  concentrators — Frues 
and  Unions.  The  hoist  is  run  by  Avater  power,  and  at  present  is  situ- 
ated near  the  inner  end  of  the  long  tunnel.  It  is  planned  to  raise  the 
shaft  to  the  surface.  The  mine  and  premises  are  lighted  by  electricity. 
Ore  is  sent  out  of  the  mine  in  long  trains  of  cars  hauled  by  a  horse. 
The  cyanide  plant  has  a  capacity  of  56  tons  daily,  a  percolation  plant 
of  50  tons,  and  an  agitation  plant  of  6  tons.     A  chlorination  plant  was 

in  course  of  construction    in  July.     There  are  100  men  employed. 

Charles  E.  Uren,  superintendent. 

Republican  Mine. — It  is  ^  mile  from  Jacksonville,  and  comprises  a 
group  of  claims  on  the  main  lode,  the  principal  ones  being  the  Repub- 
lican and  Mammoth.  The  principal  ore-shoot  thus  far  developed  is 
from  2  to  8  feet  in  width.  There  remains  much  of  the  hanging-wall 
country  to  explore,  however,  and  satisfactory  developments  may  be 
expected  in  that  direction.  A  tunnel  has  been  run  750  feet  through  the 
foot-wall  country  of  the  Mammoth  claim  to  the  vein,  and  a  shaft  sunk 
in  the  tunnel  430  feet.  The  main  shaft  in  the  Republican  is  down  400 
feet,  with  four  levels  opened.  The  company  has  a  mill  of  10  stamps  at 
the  mouth  of  the  Mammoth  tunnel,  though  at  present  operating  only 
the  Republican,  the  ore  being  hauled  by  wagons.  The  mill  has  4 
Frue  vanners.  A  large  air-compressor  is  situated  at  the  mill,  a  pipe- 
line running  to  the  Republican  shaft  for  the  purpose  of  operating  air 
drills.  The  mill  and  compressor  are  run  by  water  power,  the  company 
owning  a  ditch  and  flume  several  miles  in  length;  but  owing  to  a 
scarcity  of  water  the  past  three  years,  this  power  has  not  been  available 
during  the  summer  and  fall  months.     The  hoist  at  the  Republican  is 


134  •  CALIFORNIA   STATE   MINING   BUREAU. 

run  by  steam.  Water  is  removed  from  the  mine  by  means  of  a  valve 
bucket,  which  discharges  automatically  upon  reaching  the  surface. 
This  is  accomplished  by  means  of  a  tipple.  The  bucket  is  hoisted  until 
it  reaches  a  section  of  the  skidway,  which  is  movable,  being  secured  in 
place  by  a  strong  iron  rod  passing  through  this  section  at  a  point  some- 
what above  its  center.  Being  brought  to  a  state  of  rest,  the  weight  of 
the  bucket  and  contained  water  causes  the  tipple  to  move  from  an 
inclined  to  a  vertical  position,  the  bucket  being  then  let  down  until  the 
center  pin  of  the  valve  in  the  bottom  resting  upon  the  floor  of  the 
water-dump  causes  it  to  discharge  its  contents,  which  flow  away;  a 
counter  weight  upon  the  tipple  causes  it  to  resume  its  normal  position, 
carrying  with  it  the  empty  bucket,  which  may  then  again  descend  into 
the  mine.  There  are  22  men  employed. Republican  Mining  Com- 
pany of  San  Francisco,  owners.  T.  F.  McGovern  of  Chinese,  superin- 
tendent. 

Clio  Mine. — This  is  ^  mile  south  of  .Jacksonville.  It  has  recently 
been  equipped  with  a  new  steam  hoist  and  a  10-stamp  mill,  the  boilers 
(generating  steam  for  both  hoist  and  mill)  being  located  at  the  mill 
several  hundred  feet  distant  down  the  hill  from  the  hoist.  A  shaft  had 
been  sunk  170  feet  about  the  middle  of  July,  at  which  time  the  mine 
was  not  in  operation,  all  the  work  in   progress  being  at  the  mill,  which 

was  in  course  of  construction. J.  E.   Potter  of  .Jacksonville,  owner 

and  superintendent. 

Southward  from  the  Clio,  no  mines  are  in  operation  on  the  Central 
Lode  in  this  county,  excepting  some  prospecting  in  one  or  two  mines. 

Golden  Gate  Mine. — It  is  1  mile  southwest  of  Sonora,  and  is  one  of  the 
principal  mines  of  this  county.  It  has  been  in  continuous  operation  for 
ten  years,  and  has  been  a  large  and  steady  producer.  The  formation  is 
amphibolite  schist,  striking  N.  10°  E.,  dipping  to  the  eastward.  Through 
this  the  Golden  Gate  vein  strikes  about  N.  60°  E.  The  strike  is  some- 
what variable.  The  dip  also  varies  from  35  to  65  degrees.  Thus  the 
vein  does  not  conform  in  either  strike  or  dip  with  the  inclosing  forma- 
tion. At  three  points  in  the  underground  workings  of  the  Golden  Gate 
Mine  I  found  veins  of  quartz  coming  in  from  the  hanging-wall  side  of 
the  Golden  Gate  vein.  One  of  these  appears  on  the  200-foot  level,  500 
feet  in  a  northeasterly  direction  from  the  shaft.  This  vein  is  from  6  to  8 
feet  in  width,  showing  no  indications  of  value.  This  vein  has  an  appar- 
ent dip  to  the  eastward  of  50  to  65  degrees.  It  does  not  cross  the  Golden 
Gate  fissure,  but  stops  at  the  hanging-wall.  Another  instance  of  the 
occurrence  of  a  vein  in  the  hanging-wall  is  found  on  the  300-foot  leveh 
450  to  500  feet  northeast  of  the  shaft  of  the  Golden  Gate.  Here  is 
found  a  large  stope  with  intermediate  levels — one  20  feet  above,  the 
other  25  feet  below,  the  300-foot  level.     The  mineral  zone  of  the  Golden 


THE    MOTHER    LODE    ^REGION — TUOLUMNE    COUNTY.  135 

Gate  Mine  is  here  large,  and  the  stopes  are  wide.  At  the  point  indi- 
cated a  vein  having  a  strike  parallel  with  the  Golden  Gate  fissure  with 
a  dip  of  40  degrees  to  the  northwest  cuts  completely  through  the  Golden 
Gate  fissure,  passing  into  the  foot-wall.  This  vein  is  about  2  feet  in 
width.  It  shows  no  sign  of  valuable  mineralization,  and  has  not  been 
worked,  excepting  where  it  intersects  the  stopes  of  the  Golden  Gate  Mine. 

One  other  instance  of  the  occurrence  of  a  vein  of  quartz  from  the 
direction  of  the  hanging-wall  is  found  on  the  400-foot  level,  where  a 
small  vein  about  1  foot  in  width  intersects  the  Golden  Gate  vein,  pass- 
ing into  the  foot-wall.  It  is  perpendicular,  and  cuts  the  Golden  Gate 
vein  near  a  right  angle;  it  shows  no  sign  of  value. 

On  the  500-foot  level  the  main  drift  diverges,  the  hanging-wall  branch 
following  a  gouge  and  the  foot-wall  branch  following  a  small  lens  of  ore. 
Thirty  feet  from  the  point  of  divergence  in  the  foot-wall  branch  is  a 
cross-cut  extending  nearly  100  feet  into  the  foot-wall,  all  in  the  hard 
greenstone,  with  no  ore. 

The  principal  shaft  is  down  700  feet,  with  a  winze  200  feet  below  the 
700-foot  level  at  a  point  some  distance  northeast  of  the  shaft.  There  are 
ten  levels  in  the  mine,  three  of  which  are  above  the  collar  of  the  shaft. 
Considerable  development  was  in  progress  in  these  upper  levels,  some 
excellent  ore  being  found.  The  property  is  equipped  with  hoist  and  20- 
stamp  mill,  and  has  electric,  steam,  and  water  power.  There  are  also  a 
slimes  plant  and  a  chlorination  works  attached  to  the  mine.  Joseph 
Francis,  who  is  foreman  of  the  mine,  has  invented  a  simple  device  in  the 
form  of  a  swinging  apron  of  iron  for  use  on  loading  chutes,  by  means  of 
which  the  chutes  may  be  constructed  so  as  to  require  less  room  than 
they  usually  do,  the  apron  being  turned  upward  or  allowed  to  hang 
beneath  the  chute  when  not  in  use.  The  employment  of  these  simple 
devices  not  only  results  in  convenience,  but  also  effects  a  saving  of  time 

and  money.     There  are  70  men  employed. Golden  Gate  and  Sulphuret 

Mining  and  Development  Company,  owner.  J.  Fisher  of  Sonora,  super- 
intendent. 

Densmore  Mine. — It  is  3  miles  northwest  of  Columbia,  overlooking  and 
partly  in  the  canon  of  the  Stanislaus.  The  mine  was  discovered  many 
years  ago,  but  was  developed  in  a  superficial  manner  by  the  owner, 
who  was  unable  to  do  more  than  assessment  work  on  it.  No  one  con- 
sidered it  of  more  than  nominal  value.  Within  the  past  two  years^ 
however,  it  has  changed  ownership  a  number  of  times,  and  it  is  being 
developed  systematically.  The  formation  is  grano-diorite,  and  it  is  per- 
tinent to  here  remark  that,  regardless  of  the  prejudice  in  the  minds  of 
some  against  granite  as  a  yielder  of  profitable  ore-bodies,  some  of  the 
deepest  and  best  mines  in  California,  as  well  as  elsewhere,  are  in  granite 
or  grano-diorite.  On  the  Densmore  a  tunnel  has  been  driven  on  the  vein 
a  distance  of  400  feet  and  a  shaft  sunk  400  feet  from  the  surface,  inter- 


136  CALIFORNIA    STATE    MINING    BUREAU. 

secting  the  tunnel.  This  is  at  present  the  principal  development  and  has 
exposed  an  ore-shoot  200  feet  long,  400  feet  high,  with  an  average  thick- 
ness of  about  5  feet.  In  places  it  is  12  feet  wide.  This  ore,  it  is  stated, 
will  average  -ll?  per  ton.  Some  portions  are  heavily  sulphuretted,  and 
run  from  $150  to  $250  per  ton.  Of  this,  former  owners  shipped  during 
1899-1900  over  $26,000  worth,  net.  In  addition  to  the  above  described 
development  there  are  several  other  tunnels,  shafts,  winzes,  etc.  A  main 
tunnel  was  being  driven  200  feet  lower  than  the  one  above  referred  to, 
which  will  deliver  ore  into  the  bin  of  the  mill,  which  consists  of  two 
batteries  of  2  stamps  each,  with  one'  Wilfley  concentrating  table.  A 
cyanide  plant  of  10  tons  daily  capacity  also  forms  part  of  the  equipment. 
Though  in  a  rugged  canon,  the  mine  is  favorably  situated  for  economic 
working,  by  means  of  adits,  which  will  command  over  600  feet  of  backs, 
and  then  another  tunnel  may  be  driven  still  lower  if  desired.  A  ditch 
owned  by  the  Utica  Company  passes  along  the  mountain  side  opposite 
the  mine,  and  will  afford  a  cheap  power;  and,  taken  altogether,  it  is 
one  of  the  most  favorably  situated  mines  in  the  county.     There  were  20 

men  employed  the  latter  part  of  June. Hayward  &  Lane  of  San 

Francisco,  owners.     L.  R.  Poundstone  of  Columbia,  superintendent. 

Confidence  Mine. — It  is  12  miles  east  of  Sonora,  at  an  altitude  of  about 
4000  feet,  in  the  granite  area  lying  east  of  the  Calaveras  formation. 
This  is  one  of  the  most  noted  mines  in  the  county,  and  has  been  worked 
for  years,  producing,  it  is  claimed,  upward  of  $5,000,000.  The  vein 
strikes  N.  14°  W.,  and  dips  east  at  18°  to  30°.  The  inclined  shaft  has 
reached  a  depth  of  810  feet,  with  a  winze  200  feet  below  the  800-foot 
level.  The  mine  makes  less  than  60  gallons  of  water  a  minute.  The 
vein  varies  from  a  few  inches  to  15  feet  in  thickness.  The  granite  is 
much  decayed  from  the  surface  to  a  depth  of  300  feet,  below  which  is 
found  a  hard,  normal  grano-diorite.  A  light-colored  dike  rock,  frequently 
of  pale-green  color,  due  to  chlorite,  is  usually  an  accompaniment  of  the 
vein.  The  ore  is  free  milling,  but  contains  a  sulphide  mineral  difficult 
to  concentrate.  C3'anide  experiments  are  being  made  on  this  mineral 
and  also  on  the  coarse  sands  which  are  separated  from  the  tailings  by 
means  of  a  form,  of  spitzkasten.  Seventy  per  cent  of  the  material  is 
coarse  sand,  containing  95  cents  per  ton.  The  remaining  material  goes 
to  a  Gates  canvas  plant.  The  total  loss  in  tailings  is  $1.65  per  ton. 
The  slimes  below  the  canvas  tables  still  contain  $3  per  ton.  This  is  the 
material  to  be  experimented  upon  with  the  cyanide  process,  but,  due  to 
its  extreme  fineness,  the  percolation  method  cannot  be  employed.  The 
property  is  equipped  with  a  steam  hoist  and  30-stamp  mill,  of  which 
20  were  dropping.  A  No.  24  punched  tin  screen  is  used,  the  discharge 
being  from  7  to  8  inches  high.  The  capacity  is  3  tons  per  stamp.  There 
are  3  concentrators  with  6-foot  belts,  and  4  with  4-foot  belts.  Tailings 
are  run  onto  the  canvas  tables  9  hours  before  purifying.     The  experi- 


THE  MOTHER  LODE  REGION — TUOLUMNE  COUNTY.  137 

raent  of  purifying  was  tried,  but  proved  unsatisfactory. ■^ Confidence 

Gold   Mining  Company  of  San    Francisco,  owners.     N,  Carmichael  of 
Confidence,  superintendent. 

Black  Oak  Mine. — It  is  -h  mile  southwest  of  Soulsbyville,  on  the 
East  Lode,  and  includes  the  Black  Oak,  Carra,  and  Live  Oak  claims. 
The  mine  was  discovered  about  'thirty  years  ago,  and  during  its  early 
history  gained  little  fame,  but  within  the  past  five  years  it  has  come  to 
be  recognized  as  one  of  the  most  important  mines  in  the  State.  It 
occurs  in  grano-diorite.  The  vein  varies  from  1  to  25  feet  in  width,  and 
has  several  branches  coming  in  from  the  hanging-wall  side.  These 
latter  often  contain  heavy  sulphide  mineral  of  high  grade.  Thousands 
of  tons  of  this  class  of  ore  have  been  shipped  to  Selby's.  The  deepest 
shaft  is  down  900  feet,  at  an  angle  approximately  65  degrees,  the  dip 
being  westerly  and  the  strike  north  and  south.  The  vein  is  intersected 
at  intervals  by  dikes  of  very  hard  dark-green  diorite.  These  simply  dis- 
place the  vein.  One  at  the  northern  end  is  evidently  in  the  plane  of  a 
fault  fissure,  as  the  vein  does  not  reappear  on  the  north  side  of  the  dike, 
as  in  previous  instances  farther  southward.  The  throw  is  presumed  to 
be  to  the  westward.  If  this  assumption  be  correct,  the  Genevieve  Mine, 
Wing  about  4000  feet  to  the  northward,  may  be  the  real  extension  of 
the  Black  Oak  vein.  The  mine  is  equipped  with  steam  and  water-power 
hoist  and  a  30-stamp  mill.  A  large  slimes  plant  also  forms  an  important 
feature  in  the  beneficiation  of  the  ores.  The  ores  are  quartz,  containing 
iron,  copper,  lead,  and  zinc  sulphides.  Pyrrhotite,  a  magnetic  iron  sul- 
phide of  bronze  color,  is  a  prominent  constituent  of  the  ores,  and  is 
characteristic  of  the  granite  veins  on  the  East  Lode.  In  the  mill  a 
60-mesh  screen  is  in  use,  the  discharge  being  6  inches  high.  The 
30  stamps  crush  35  tons  daily,  which  is  an  unusually  low  duty  for 
stamps  in  California,  but  is  probably  due  to  the  hardness  of  the  rock 
and  the  fineness  of  the  screen.  The  management  claims  to  be  able  to 
make  a  higher  saving  by  fine  crushing.  There  are  10  concentrators  in 
the  mill.  The  pulp  from  the  batteries  passes  to  the  plates  and  thence 
to  the  vanners.  Forty  per  cent  of  the  gold  is  saved  in  the  batteries. 
From  the  vanners  all  tailings  go  to  the  canvas  plant,  consisting  of  two 
floors  60  X  100  feet.  From  the  canvas  tables  the  pulp  is  elevated  and 
sent  to  the  cyanide  vats,  where  it  is  charged  by  means  of  a  mechanical 
device  to  insure  an  equal  distribution  of  sands  and  slimes,  and  to  pre- 
vent as  far  as  possible  the  formation  of  channels  in  the  charge.  The 
pulp  is  treated  by  the  percolation  method  for  80  hours,  and  then  dis- 
charged through  the  side  doors  into  the  creek.  A  60-ton  tank  is  sluiced 
out  in  one  hour  with  water  under  a  500-foot  head.  Sulphurets 
obtained  from  the  vanners  and  from  canvas  tables  are  worked  in  a  sepa- 
rate plant  by  agitation  for  a  period  of  36  hours,  with  an  extraction  of 
94  per  cent.     The  strength  of  cyanide  solution  employed  on  the  tailings 


138  CALIFORNIA    STATE    MINING    BUREAU. 

is  0.25  per  cent;  that  in  the  agitation  process  varies  somewhat  according 

to  the  value  of   the  ore.     There  are  50  men  employed. Scott,  Dow 

&  Co.,  owners.     W.  P.  Scott  of  Soulsbyville,  superintendent. 

Eureka  Con.  {Dead  Horse)  Mine. — It  is  on  the  East  Lode,  at  Carters. 
The  deepest  shaft  is  down  1550  feet.  The  formation  is  mica  schist  of 
the  Calaveras  formation.  The  vein  is  from  1  to  12  feet  wide,  and  con- 
sists of  quartz  and  pyrite.  The  hoist  and  mill  are  run  by  water  when 
available.  The  mill  has  20  stamps  of  900  pounds  weight.  There  are 
8  Frue  concentrators  in  the  mill.  Formerly  a  canvas  plant  was  opera- 
ted in  connection  with  the  mill,  but  its  use  has  been  discontinued.  A 
cyanide  plant  on  the  property  treats  2  tons  of  sulphides  daily.  This  is 
on  concentrates  from  van ners. '  The  screen  in  the  battery  is  38-mesh. 
It  is  claimed  that  the  extraction  is  about  90  per  cent.  There  are  41 
men  employed. Alvinza  Hay  ward  and  Hobart  Estate  of  San  Fran- 
cisco, owners.     E.  T.  Kane  of  Carters,  superintendent. 

Providence  {Gloster)  Mine. — This  property  is  2  miles  southeast  of  Car- 
ters, in  the  canon  of  the  North  Fork  of  Tuolumne  River.  Since  the 
last  report  this  mine  has  come  into  prominence  as  a  rich  producer.  It 
was  systematically  opened  during  1896-97,  and  equipped  with  hoist 
and  milling  plant,  to  accommodate  which  expensive  grading  and  road- 
making  were  required,  as  the  slope  of  the  mountain  is  nearly  35  degrees. 
A  mile  and  a  half  of  road,  reaching  from  the  bottom  of  the  canon  to 
the  mine,  cost  $5,000.  The  vein  occurs  in  the  black  slates  of  the  Cala- 
veras formation,  and  will  average  5  feet  in  width  in  the  pay  shoot.  The 
quartz  contains  li  per  cent  of  sulphides.  The  shaft  is  down  850  feet, 
with  six  levels.  The  mill  has  10  stamps,  but  was  not  in  operation  in 
July  last.  Only  development  work  was  in  progress  in  the  mine.  All 
power  is  steam,  water  being  very  scarce  in  that  locality.  There  are  12 
men  employed,  though  the  full  force  is  30  when  the  mill  is  in  opera- 
tion.  Tuolumne  County  Mining  Company,  owner.     C.  A.  Holland 

of  Carters,  superintendent. 

Goldwin  Mines. — This  constitutes  a  group  of  three  claims  about  a  mile 
westerly  from  the  Providence  Mine,  and  10  miles  southeast  of  Sonora. 
The  elevation  is  about  2000  feet.  The  strike  is  north  and  south,  and 
the  dip  east.  Geologically,  the  property  consists  of  a  broad-fissured 
zone  with  a  system  of  parallel  quartz  veins  of  variable  width,  from  2  to 
5  feet.  The  veins  are  often  found  accompanied  by  a  light-colored  dike. 
The  formation  is  a  fine-grained  mica  schist.  The  quartz  vein  is  usually 
banded,  and  contains  auriferous  sulphides.  A  tunnel  has  been  driven 
850  feet  on  the  vein  and  a  shaft  sunk  250  feet,  in  addition  to  which 
there  are  several  short  tunnels  and  winzes.  The  property  is  equipped 
with  a  substantial  hoist  driven  by  air,  and  a  water-driven  air-com- 
pressor.    The  company  has  constructed  a  dam  in  the  caiion  and  built  a 


THE    MOTHER    LODE    REGION — TUOLUMNE    COUNTY.  139 

flume  to  the  mill  site,  thus  having  free  water-power.  It  is  reported  that 
this  property  has  produced  $150,000.  It  had  been  idle  for  many  years 
before  coming  into  the  hands  of  the  present  owners.     There  are  25  men 

employed. Goldwin  Con.  Mines,  owner.    W.  H.  McClintock  of  Sonora, 

superintendent. 

Dreisam  (liJaston)  Mine. — It  is  on  the  East  Lode,  at  Arrastraville.  The 
vein  is  from  12  inches  to  3  feet  in  width,  and  is  in  grano-diorite.  A 
shaft  had  been  sunk  to  300  feet  in  July,  and  still  sinking.  The  hoist  is 
equipped  with  both  steam  and  water  power.  The  mill  has  two  batteries 
of  6  stamps  each,  and  two  Frue  concentrators.    The  mill  is  to  be  enlarged. 

There  are  30  men  employed. Dreisam  Gold  Mining  Company  of  San 

Francisco,  owner.     W.  Morehead,  superintendent. 

Grizzly  Mine. — It  is  1  mile  south  of  Carters,  on  the  East  Lode.  The 
vein  is  10  feet  in  width,  has  a  banded  structure  in  Calaveras  slate,  with 
the  usual  accompanying  dike.  The  shaft  is  down  750  feet,  with  levels 
at  intervals  of  100  feet.  The  mill  has  20  stamps,  with  8  Frue  vanners- 
Water  furnishes  power  for  both  hoist  and  mill.     From  16  to  20  men 

were  employed  in  July. Grizzly  Mining  Company  of  San  Francisco? 

owner.     W.  R.  Hall  of  Carters,  superintendent. 

Big  Oak  Flat  District. — Since  the  last  report  there  has  been  much 
activity  in  and  near  Big  Oak  Flat.  A  score  or  more  prospects  of  greater 
or  less  prominence  have  been  incorporated  and  a  large  sum  of  money 
expended  in  their  equipment  and  development.  As  is  usual  in  such 
cases,  some  of  these  have  proven  unsatisfactory  and  have  been  aban- 
doned, while  others  are  still  developing,  with  fair  prospects. 

'  Longfellow  Mine. — It  is  at  Big  Oak  Flat,  and  is  generally  considered 
as  being  on  the  East  Lode,  though  this  section  is  really  between  the 
Central  and  East  Lodes.  The  geology  of  the  mine  as  described  by  the 
superintendent  is  as  follows:  There  are  two  veins  about  50  feet  apart, 
the  foot-wall  vein  being  10  to  12  feet  wide  and  the  hanging-wall  vein 
4  to  5  feet  wide.  There  are  many  stringers  of  quartz  in  the  slaty  zone 
inclosed  between  these  two  veins.  The  formation  is  slate.  A  shaft  had 
been  sunk  to  450  feet  in  July  last.  The  surface  equipment  consists  of 
a  steam  hoist  and  a  10-stamp  mill,  with  Wiltley  and  Frue  concentra- 
tors. A  30-ton  cyanide  plant  was  in  course  of  construction  the  latter 
part  of  July,  and  the  tailings  are  to  be  treated  by  that  method.  During 
the  dry  season  water  for  milling  is  pumped  from  the  Mississippi  shaft 

sunk  on  a  vein  in  the  granite  of  Big  Oak  Flat. Longfellow  Gold 

Syndicate  of  Glasgow,  owners.  A.  P.  Dron  of  Big  Oak  Flat,  superin- 
tendent. 


140  CALIFORNIA    STATE   MINING    BUREAU. 

Mack  Mine. — This  adjoins  the  Longfellow  on  the  east,  and  is  on  the 
same  vein.  The  shaft  is  down  430  feet  at  35  degrees.  Four  levels  are 
opened,  and  the  prospect  is  stated  to  be  encouraging.  The  mine  had  a 
steam  hoist  but  no  mill  in  the  latter  part  of  July.     There  are  12  men 

employed. Mack  Con.   Mining  Comj^any  of  San  Francisco,  owner. 

C.  L.  Lang  of  Big  Oak  Flat,  superintendent. 

A  Gold-Bearing  Zone. — This  is  found  about  1  mile  west  of  Big  Oak 
Flat,  and  extends  for  more  than  15,000  feet  along  the  mountain  side, 
and  presumably  could  be  traced  farther.  The  formation  consists  of  a 
succession  of  black  slates  and  diabase  tuff.  A  description  of  the  Criss- 
Cross  claim  will  answer  in  a  general  way  for  all  of  the  numerous  claims 
along  this  belt  for  a  considerable  distance  in  either  direction  from  it. 
In  that  property  the  formation  consists  of  Calaveras  slates,  and  reefs  of 
diabase  tuff.  The  slates  occur  in  zones,  some  of  which  are  relatively 
soft  and  contain  disseminated  iron  sulphides.  The  remaining  portion 
of  the  slates  is  usually  hard,  and  less  highly  mineralized.  The  slates 
are  also  intruded  by  dikes  of  diabase  and  porphyry.  There  are  devel- 
oped in  this  mine  four  zones  of  what  are  termed  by  the  miners  "mineral 
or  metallic  slates.  "  These  zones  are  separated  from  each  other  by  dikes 
of  variable  width,  not  exceeding  20  feet.  The  slates  strike  north  30"^ 
W.,  standing  vertical.  The  entire  formation  is  intersected  by  seams  and 
veins  of  quartz,  which  strike  about  N.  30'^  E.,  dipping  southeasterly  at 
60°  to  70°.  Some  of  these  quartz  veins,  small  at  the  surface,  widen  to 
24  inches  or  more  within  a  depth  of  50  feet,  and  carry  disseminated 
gold,  proving  that  these  are  not  exclusively  pocket  mines,  as  has  been 
supposed.  These  vertical  veins  of  quartz  occur  at  intervals  of  8  to  10 
feet,  having  approximately  a  parallel  strike.  A  second  series  of  quartz 
veins  is  found  lying  nearly  horizontal,  cutting  the  slates,  and  intersect- 
ing the  vertical  veins.  These  veins  occur  at  distances  of  4  to  6  feet 
apart,  dipping  at  a  low  angle  to  the  westward,  thus  dividing  the  forma- 
tion into  rhomboidal  blocks.  Frequently  at  the  intersection  of  these 
highly-inclined  and  flat  veins  a  slight  dislocation  may  be  noticed,  indi- 
cating that  there  has  been  some  movement  of  the  formation  since  these 
veins  were  formed.  The  gold  found  in  this  property  is,  as  far  as  known, 
confined  almost  exclusively  to  the  zones  of  "  metallic '"  slates.  In  that 
portion  of  the  property  to  the  northward  the  steeply-inclined  veins  have 
been  found  to  carry  coarse  gold  in  considerable  quantity ;  in  fact,  to 
such  an  extent  that  many  thousands  of  dollars  have  been  taken  from 
rather  superficial  development  by  pocket-hunters.  To  the  southward, 
however,  the  gold  in  the  veins  has  been  found  chiefly  in  the  nearly 
horizontal  seams  and  veins,  and  these  have  all  jDroduced  largely.  The 
cause  of  this  difference  in  the  occurrence  of  the  gold  has  not  yet  been 
ascertained,  but  the  fact  that  such  is  the  case  is  of  interest.  As  a  result 
of  the  operations  of  the  pocket-miners  there  has  been  accumulated  in 


THE    MOTHER    LODE    REGION — TUOLUMNE    COUNTY.  141 

the  different  dumps  hundreds  of  tons  of  material,  which,  to  the  pocket- 
miner,  is  waste,  but  it  has  been  found  by  repeated  tests  that  all  of  these 
dumps  carry  considerable  value  in  gold.  It  is  an  established  fact  that 
the  slates  on  either  side  of  vertical  veins  carry  gold  for  a  distance  of 
2  feet  or  more  from  the  vein.  This  also  seems  to  be  the  case  with  the 
horizontal  veins.  It  may  be  that  the  gold-bearing  zones  constitute  a 
milling  proposition,  and  that  not  only  the  quartz  veins,  but  the  slates 
as  well,  may  be  mined  and  milled  as  a  whole.  In  this  respect  these 
gold-bearing  zones  bear  some  resemblance  to  the  Jumper  Mine  near 
Stent,  in  this  county,  where  it  has  been  found  that  the  most  economical, 
and  withal  the  most  successful  method  of  operating  is  to  mine  all  the 
material  between  the  walls  of  the  zone  and  the  milling  of  all  such 
material,  there  being  practically  no  waste. 


142  CALIFORNIA    STATE    MINING    BUREAU. 


MARIPOSA  COUNTY. 


Since  the  publication  of  the  last  report  of  the  State  Mineralogist,  Mari- 
posa County  has  taken  on  more  active  life.  The  Mariposa  Grant,  cover- 
ing an  area  of  about  70  square  miles,  which  for  many  years  had  lain 
idle,  has  become  the  property  of  the  Mariposa  Commercial  and  Mining 
Company,  which  has  undertaken  the  active  exploration  and  development 
of  at  least  five  of  the  most  important  mines  on  the  Grant.  They  are 
going  about  this  in  a  business-like  way,  and  the  indications  are  that  if 
there  is  any  actual  merit  in  the  mines  on  the  Grant  it  will  be  ascertained 
by  the  present  operators.  A  hasty  visit  was  made  to  this  field  of  opera- 
tion in  the  latter  part  of  May  last  for  the  purpose  of  investigating  what 
had  been  done  and  what  was  expected  of  these  mines  in  the  future. 

Mariposa  Mine.— This  property,  worked  many  years  ago,  it  is  reputed 
at  one  period  with  great  success,  but  which  had  been  idle  for  more  than 
thirty  years,  has  been  reopened,  and  an  inclined  shaft  sunk  which  had 
reached  a  depth  475  feet  on  May  15th.  The  shaft  was  carried  down  at 
a  uniform  angle,  but  the  vein  passed  out  into  the  hanging- wall  at  about 
400  feet  from  the  surface.  In  cutting  a  station  at  475  feet,  the  vein  was 
discovered  in  the  hanging-wall.  The  walls  are  diorite-porphyrite,  and 
very  hard.  The  vein  has  little  or  no  gouge,  but  generally  breaks  free  ' 
from  the  walls.  The  center  of  the  vein  is  usually  massive,  with  a  banded 
structure  near  the  walls,  and  in  some  portions  the  entire  vein  shows  the 
banded  structure.  It  varies  greatly  in  width,  from  a  seam  to  12  feet  or 
more.  It  strikes  N.  70°  W.,  with  a  variable  dip  to  the  southward,  which 
wall  average  about  60  degrees.  Several  hundred  feet  west  of  the  new 
shaft  a  branch  breaks  into  the  foot-wall,  striking  N.  50°  W.  A  shaft, 
now  caved  and  filled  with  water,  is  sunk  at  the  point  of  divergence.  It 
is  said  that  large  amounts  of  gold  were  taken  from  this  shaft  in  the  form 
of  pockets  by  the  early  miners.  A  report  of  Dr.  R.  W.  Raymond, 
"Mineral  Resources  West  of  the  Rocky  Mountains,"  1868,  states  that 
the  Mariposa  Mine  was  closed  at  that  time,  for  the  reason  that  mining 
operations  were  no  longer  profitable,  though  the  rock  contained  nearly 
$10  gold  per  ton.  It  has  been  ascertained  by  careful  sampling  of  the 
faces  of  the  stopes  abandoned  years  ago,  that  considerable  bodies  of  rock 
were  left,  which  averaged  over  $7  per  ton,  where  the  vein  was  from  2  to 
4  feet  in  width.  During  the  past  summer  a  long  drift  on  the  400-foot 
level  has  cut  through  a  fine  shoot  of  high-grade  ore.  The  mine  is 
equipped  with  steam  hoist  and  air-compressor,  steam  pumps,  and  other 


THE    MOTHER    LODE    REGION — MARIPOSA    COUNTY.  143 

necessary  machinery.  There  are  28  men  employed, Mariposa  Com- 
mercial and  Mining  Company,  owners,  320  Sansome  Street,  San  Francisco. 
J.  H.  MacKenzie,  Mount  Bullion  P.  0.,  general  manager. 

The  Princeton  Mine. — This  property,  situated  at  Princeton,  6  miles 
northerly  from  Mariposa,  has  also  been  reopened  after  an  idleness  of 
many  years.  A  new  inclined  shaft  has  been  sunk  to  a  depth  of  600  feet, 
penetrating  some  little  distance  below  the  old  workings,  very  little  of 
which  are  at  present  accessible.  Near  the  bottom  of  the  shaft,  two  fine- 
grained, ash-colored  dikes  intersect  the  vein  at  an  oblique  angle.  They 
have  not  '"thrown"  the  vein,  simply  passed  through  it.  In  the  bottom 
of  the  shaft,  at  the  time  of  my  visit,  the  vein  was  about  4  feet  in  width, 
of  beautiful  banded  quartz.  The  entire  vein  from  the  surface  to  the 
600-foot  level  is  inclosed  in  the  typical  clay  slates  of  the  Mariposa  beds. 
These  slates  differ  very  materially  from  the  black  tufaceous  slates  so 
closely  associated  with  the  rich  ore  dej^osits  of  Amador  County,  and  to 
which  more  particular  reference  is  made  under  the  head  of  Amador 
County. 

At  this  writing,  the  latter  part  of  May,  nothing  more  can  be  said  of 
the  Princeton  Mine,  and  only  the  future  development  of  the  property 
can  determine  its  real  merit.  The  mine  has  an  authentic  record  exceed- 
ing $3,000,000  to  a  depth  of  600  feet.  In  the  foot-wall  country,  lying 
immediately  west  of  the  Princeton  vein,  there  are  many  veins,  both  large 
and  small,  of  gold-bearing  quartz,  and  this  section  it  is  the  intention  of 
the  company  to  prospect.  The  mine  is  equipped  with  steam  hoisting 
plant  and  machine  shop,  and  a  10-stamp  mill  is  being  erected  for  the 
purpose  of  testing  ores  from  the  several  mines  of  the  Grant.  The  central 
office  of  the  mines  is  located  at  Princeton.  There  are  30  men  employed. 
In  the  middle  of  September  the  shaft  was  down  nearly  900  feet,  the  vein 

averaging  3^  feet  in  width. J.  H.  MacKenzie,  Mount  Bullion  P.  0., 

general  manager. 

The  Josephine  Mine. — This  property  is  about  3  miles  north  of  Bear 
Valley,  overlooking  the  Merced  River,  and  immediately  adjoins  the 
"  Pine  Tree,"  with  which  its  name  is  usually  associated.  This  is  also 
being  operated  by  the  Mariposa  Commercial  and  Mining  Company.  The 
manager  has  placed  a  hoist  underground,  and  sunk  a  winze  200  feet 
from  the  level  of  the  "English"  trail  drift.  A  vigorous  policy  has  been 
inaugurated,  and  the  vein  will  be  developed  as  rapidly  as  possible.  It 
has  been  stated  in  numerous  previous  reports  that  the  Josephine  vein 
splits  off  to  the  westward  from  the  Pine  Tree  vein ;  that  it  continues  upon 
an  independent  course  for  a  distance  of  nearly  15  miles,  rejoining  the 
main  lode  near  Pifion  Blanco,  3  miles  north  of  Coulterville.  A  careful 
investigation  has  led  to  the  conclusion  that  the  Josephine  vein  returns 
to  and  rejoins  the  Pine  Tree  vein  within  a  distance  of  3000  feet  from 


144  CALIFORNIA    STATE    MINING    BUREAU. 

where  it  diverges,  at  what  is  called  the  old  Fremont  shaft.  The  error 
into  which  myself  as  well  as  others  have  been  led  was  in  presuming  that 
a  line  of  disconnected  croppings  represented  the  Josephine  vein,  whereas 
the  croppings  of  the  Josephine  are  absolutely  continuous,  and  may  be 
traced  from  its  point  of  divergence  from  the  Pine  Tree  northward  to 
where  it  rejoins  the  Pine  Tree  vein.  The  hills  are  covered  with  a  dense 
growth  of  chaparral,  manzanita,  and  greasewood,  and  the  tracing  of 
this  line  of  croppings  was  not  an  easy  task,  though  not  an  impossible 
one. 

Both  the  Pine  Tree  and  the  Josephine  veins  are  well  exposed  on  the 
level  of  the  English  trail  drift,  where,  taking  a  cross-section  at  a  point 
437  feet  below  the  croppings  at  the  Fremont  shaft,  it  is  found  that  the 
two  veins  converge  on  this  level  about  400  feet  north  of  the  point  of 
meeting  on  the  croppings,  showing  that  the  line  of  convergence  is  not 
vertical,  but  inclined  to  the  northward.  A  cross-cut  at  the  point  where 
these  veins  converge  on  the  English  trail  level,  shows  a  body  of  quartz 
40  feet  in  width,  dipping  uniformly  to  the  eastward  at  an  angle  of  60 
degrees.  Along  the  drift  which  follows  closely  the  Pine  Tree  vein,  the 
two  great  veins  are  separated  by  a  mere  seam  no  thicker  than  a  knife- 
blade.  Northward,  a  mass  of  soft  material  composed  of  ankerite  with 
mariposite  and  quartz,  separates  the  veins  by  a  few  feet.  Still  farther 
northward  the  divergence  is  greater,  and  the  Pine  Tree  vein  shows  a 
gouge  1  inch  thick  on  the  hanging-wall  side  of  the  vein.  A  cross-cut 
has  been  driven  25  feet  eastward  through  a  mass  of  crushed  and  highly 
altered  ankerite  to  a  second  gouge  containing  fragments  of  this  rock- 
mass.  The  gouge  is  from  1  to  2  inches  thick,  and  is  extremely  tough, 
but  soft.  The  wall  beyond  is  polished  like  a  mirror,  and  was  formerly 
considered  the  hanging-wall  of  the  vein.  The  material  beyond  the  slip 
is  identical  with  that  in  the  cross-cut  (crushed  ankerite  altering  to  talc). 
Serpentine  occurs  on  the  hanging-wall  side  of  the  vein  on  the  surface 
over  200  feet  distant.  The  serpentine  approaches  nearer  to  the  vein, 
going  northward,  however,  and  in  the  tunnel  driven  near  the  Merced 
River,  about  1000  feet  lower  than  the  English  trail  drift,  lies  on  the 
hanging- wall  side  of  a  zone  of  material  similar  to  that  found  in  the  cross- 
cut above  referred  to  (the  altered  ankerite).  The  ankerite,  containing 
mariposite,  separates  the  Pine  Tree  and  Josephine  veins,  and  the  material 
grows  broader  as  the  veins  diverge,  but  where  they  are  80  to  100  feet 
apart  and  more,  it  does  not  fill  the  entire  space  between  them — a  gray 
rock,  amphibolite  schist,  lying  next  the  ankerite. 

The  Josephine  vein  is  distinguished  everywhere  along  its  course  by 
what  may  be  termed  its  fragmental  appearance.  A  banded  structure  is 
frequently  apparent,  but  mixtures  of   quartz  and  black  slaty  material 

are  the  most  persistent  features. J.  H.  MacKenzie,  Mount  Bullion 

P.  0.,  general  manager. 


'^/  :•*.  -^ 


Croppings  of  the  Maripojsa  Vein. 


Croppings  of  the  Louisa  Mine,  Coulterville,  Mariposa  County. 


THE   MOTHER    LODE    REGION MARIPOSA    COUNTY. 


145 


Pine  Tree  Mine. — This  adjoins  the  Josephine,  and  is  3  miles  north  of 
Bear  Valley.  One  of  the  old  tunnels  driven  by  the  former  operators  has 
been  cleaned  out  and  retimbered,  and  a  hoisting  engine  set  up  under- 
ground about  600  feet  from  the  mouth.  Here  a  shaft  has  been  sunk  to 
a  depth  of  300  feet  below  the  level.  Ventilation  is  secured  by  an  upraise 
through  old  workings  above  the  hoist  connecting  with  an  upper  tunnel. 
The  engine  is  operated  by  steam  carried  in  from  the  boilers  at  the  mouth 
of  the  tunnel,  the  exhaust  passing  out  through  the  raise.  Owing  to  the 
careful  manner  in  which  the  steam  pipes  have  been  packed,  there  is 
little  condensation  in  the  pipes,  and  the  temperature  at  the  station  is 


Fig.  35. 

not  uncomfortably  warm.  In  sinking  the  shaft,  a  very  interesting  fault 
was  discovered  about  300  feet  from  the  platform,  the  character  of  which 
is  illustrated  in  the  accompanying  drawing  (Fig.  35). 

The  indications  are  that  the  formation  on  the  hanging-wall  side  of  the 
fault  has  slipped  downward,  and  that  if  sinking  were  continued  on 
that  portion  it  would  be  found  to  cut  out,  though  in  what  distance  it  is 
impossible  to  say.  The  foot-wall  portion,  however,  will  extend  down- 
ward to  indefinite  depth.  The  shaft  is  being  sunk  through  the  heart  of 
the  ore-shoot  opened  by  the  old  company,  it  being  the  purpose  to  ascer- 
tain as  quickly  as  possible  whether  payable  ore  still  remains  in  the 

10— MB 


146  CALIFORNIA   STATE    MINING   BUREAU. 

mine,  and  if  so,  how  much.  The  Pine  Tree  Mine  is  everywhere  char- 
acterized by  its  massiveness  and  its  entire  freedom  from  slaty  inclusions 
Iron  pyrite  occurs  in  the  quartz,  but  is  not  abundant.  The  vein  is 
usually  well  defined  by  smooth  walls,  the  foot-wall  being  always,  as  far 
as  observed,  mariposite  and  ankerite.  The  hanging-wall  side  of  the 
quartz  vein  is  a  granulated  mass  of  rock,  containing  many  fragments 
of  what  appear  to  be  the  ankerite.  The  real  hanging-wall — normal 
country  rock,  i.  e.,  slate,  diabase,  or  serpentine — has  not  been  cut  on  the 
English  trail  level.  At  the  mouth  of  the  old  Pine  Tree  tunnel,  now 
caved  and  inaccessible,  the  serpentine  is  found  close  to  the  vein.  South- 
ward, up  the  hill,  it  is  fully  200  feet  away  from  the  vein.  In  the  river 
tunnel  the  serpentine  forms  the  hanging-wall  of  the  vein — that  is,  it 
lies  on  the  hanging-wall  side  of  the  fragmental  rock  (crushed  ankerite) 
referred  to  as  occurring  on  the  hanging-wall  side  of  the  quartz  on  the 
English  trail  level.  In  the  river  tunnel  the  Pine  Tree  vein  splits  up 
and  makes  good-sized  quartz  veins  in  this  fragmental  material.  In 
places  the  quartz  is  confined  to  the  foot-wall  side,  ranging  in  width  from 
4  to  over  40  feet.  In  speaking  of  the  vein  the  entire  mass  of  ankerite 
with  the  included  quartz  lenses  is  meant,  though  commercially  only 
that  portion  containing  pay  ore  would  be  recognized  as  the  vein. 

Roma  and  Sierra  Blanca  (Quartz). — Three  miles  northeast  of  Col- 
orado. A  tunnel  is  being  run  1400  feet  to  reach  the  vein.  It  had 
reached  a  length  of  915  feet  September  1,  1900,  and  is  being  driven 
through  soft  slate  and  schist  at  a  cost  of  $4  per  foot,  including  timber- 
ing. All  work  is  by  hand,  and  the  tunnel  is  5  by  7  feet  clear.  The 
timbers  are  obtained  on  the  property.  There  are  12  men  employed. 
Lew  Anbury  of  Mariposa,  superintendent. 

Mary  Harrison. — This  mine  is  on  the  southern  portion  of  the  Cook 
Estate,  2  miles  south  of  Coulterville.  It  is  situated  on  the  great 
Dolomitic  vein,  the  quartz  occurring  on  the  foot-wall  side,  being  4  to  6 
feet  wide.  Both  hanging  and  foot  walls  are  diabase.  Black  clay 
slates  (Mariposa  beds)  and  serpentine  also  occur  in  the  immediate 
vicinity  of  the  vein.  The  deepest  workings  are  down  900  feet,  and  still 
sinking  in  July  last.  The  ore-shoot  is  stoped  from  the  700-foot  level 
to  the  surface.  The  lower  levels  are  extensive.  A  40-stamp  mill  built 
on  the  Potosi  Mine,  one  of  the  group  owned  by  this  company,  crushes 
ore  from  the  Mary  Harrison  Mine,  with  which  it  is  connected  by  4 
miles  of  narrow-gauge  railroad.  No  rock  was  being  crushed  at  the  time 
of  my  visit.  Hoisting  is  done  by  steam.  There  are  75  men  employed. 
In  addition  to  the  Mary  Harrison,  the  company  also  owns  the  Louisa, 
Margaret,   Potosi,  Malvina,  and  numerous  other  claims  on  this  large 

estate,  but  the  above  described  is  the  only  one  in  operation. Merced 

Gold  Mining  Company  of   Boston,   owners.     J.  Mills  of   Coulterville, 
manager. 


» 


THE   MOTHER   LODE    REGION — MARIPOSA   COUNTY.  147 

Bonanza  Mine. — It  is  5^  miles  south  of  Coulterville,  near  the  Merced 
River,  on  the  Dolomitic  vein.  A  cross-cut  tunnel  was  in  280  feet  in 
July  last,  running  to  intersect  the  vein,  which  was  said  to  be  50  feet  in 
width.  The  hanging-wall  is  slate  and  the  foot-wall  serpentine.  A 
20-stamp  mill  was  in  process  of  building,  and  a  dam  was  being  con- 
structed in  the  Merced  River  for  power.  There  are  25  men  employed. 
T.  P.  Brisland  of  Coulterville,  manager. 

Murphy  Mine. — It  is  3^  miles  south  of  Coulterville,  on  the  main 
lode,  having  serpentine  on  the  hanging-wall  and  slate  on  the  foot,  dif- 
fering in  this  respect  from  the  Mary  Harrison,  which  it  somewhat 
resembles  otherwise.  A  shaft  had  reached  a  depth  of  145  feet  the 
middle  of  July,  and  two  levels  had  been  started.  The  property  is 
equipped  with  steam  hoist,  but  has  as  yet  no  mill.     There  are  18  men 

employed. The   Guffy-Galey   Gold   Mining  Company  of  Pittsburg, 

Pa.,  owners.     W.  W.  Elmer,  superintendent. 

Black  Hill  {Pumpkin)  Mine. — It  is  1  mile  north  of  Coulterville,  and 
is  in  the  prospective  stage,  a  shaft  having  been  sunk  60  feet,  equipped 
with  horse-whim.  Some  rich  ore  has  been  found  in  recent  development. 
There  are  5  men  employed. John  Boyd,  owner.  J.  J.  Dolan  of  Coul- 
terville, superintendent. 

Yosemite  Hydraulic  Mine. — It  is  10  miles  east  of  Groveland.  The 
company  has  built  11  miles  of  ditch  flume  and  pipe-line  the  past  year, 
and  made  preparations  to  carry  on  hydraulic  mining  on  an  extensive 
■scale;  the  scarcity  of  water,  however,  has  affected  operations  seriously. 

When  working  full  force  20  men  are  employed. W.  J.  Pender  of 

Groveland,  superintendent. 


148 


CALIFORNIA   STATE   MINING   BUREAU. 


MADERA  COUNTY. 


As  it  was  necessary  to  pass  through  Madera  County  in  going  into 
Mariposa,  a  brief  examination  of  two  mines  was  made  while  in  that 
county.  In  the  neighborhood  of  Grub  Gulch  prospecting  is  actively 
being  prosecuted,  and  also  in  the  direction  of  Coarse  Gold,  but  lack  of 
time  precluded  visiting  that  section  the  past  season. 

The  Rex  Mine. — This  is  a  new  property  at  Grub  Gulch.  It  has  been 
opened  within  the  past  few  months.     An  inclined  shaft  has  been  sunk 

V&R-fiCAL  Cross  Section 

Rex  ^Oinet 


Fig.  36. 

to  a  depth  of  100  feet  at  an  angle  of  40  degrees  to  the  eastward.  At  a 
depth  of  50  feet  from  the  surface  in  this  shaft,  the  Rex  vein,  which  is 
from  a  few  inches  to  14  inches  in  width  and  rich  in  free  gold,  was  found 
intersected  by  another  vein,  known  as  the  Bullion,  which  dips  to  the 
westward  at  an  angle  of  60  degrees,  cutting  the  dip  of  the  formation 
nearly  at  right  angles  and  displacing  the  Rex  vein.     The  formation  in 


THE    MOTHER    LODE   REGION MADERA    COUNTY. 


149 


which  these  veins  occur  is  mica  schist.  That  portion  of  the  Rex  vein  in 
the  neighborhood  of  the  shaft  has  been  opened  by  a  series  of  shallow 
pits,  and  by  means  of  these  the  direction  of  its  strike  can  be  traced  along 
the  surface.  After  passing  the  Bullion  vein,  which  in  strike  intersects 
the  Rex  vein  at  a  low  angle,  the  Rex  vein  does  not  appear  in  line  with 
the  croppings  on  the  farther  side  of  the  Bullion  vein.  However,  farther 
to  the  northward  is  a  vein  which  has  the  physical  characteristics  of  the 
Rex  vein,  and  also  carrying  the  same  character  of  gold,  and  this  vein 
has  been  traced  for  more  than  1000  feet  from  its  intersection  with  the 
Bullion  vein,  on  the  opposite  side  of  which  it  can  be  no  further  recog- 
nized. There  is  little  doubt  that  these  two  disconnected  veins  are 
identical,  having  been  dislocated  by  the  later  Bullion  vein.  The  accom- 
panying  sketches    (Figs.   36   and   37)    illustrate  this  occurrence.     As 

Pi^T^N  o^  Re;(  -anp  Bullion  Veins 

a4-(5rub<^ulcH\.  madera  Counry .  Callfsmia^ 

5bowir\4    pisplaceroenr  of-  R6-;<  \/fc)H    b/ 
"^       la-fer  guLuioN   VeiiS. 


Fig.  37. 

nearly  as  could  be  determined,  the  Bullion  vein  has  displaced  the  Rex 
vein  about  70  feet,  its  downward  extension  lying  in  the  foot-wall  and 

about  that  distance  from  the  upper  portion  of  the  vein. Charles  M. 

Ward  and  others  of  Grub  Gulch,  owners. 

iVe  Flu8  Ultra  Copper  ikfme.— This  property  is  9  miles  in  a  south- 
westerly direction  from  Raymond,  on  the  San  Joaquin  plains  at  Daulton. 
It  is  an  old  property  which  has  been  reopened  since  the  publication  of 
the  last  report.  Three  shafts  have  been  sunk  on  the  mine,  125, 140,  and 
145  feet  respectively.  These  are  distributed  along  the  vein  for  a  dis- 
tance of  1000  feet.  The  formation  is  chiastolite  schist.  The  zone  of 
mineralization  is  100  feet  or  more  in  width,  in  which  there  are  several 
shoots  of  ore  having  an  approximate  parallelism  with  many  ramifying 
branches.  There  are  also  dikes  cutting  the  formation.  The  ore  normally 
is  an  iron-copper  sulphide,  but  in  the  zone  of  semi-oxidation,  between 
the  thoroughly  oxidized  gossan  ores  and  the  normal  sulphide  ores, 
oxidation  is  taking  place  very  rapidly.     This  oxidation  results  in  giving 


160  CALIFORNIA   STATE    MINING   BUREAU. 

out  a  large  amount  of  heat,  which  occasions  the  mine  workings  to  be 
unusually  hot.  The  ore  taken  from  certain  shoots  in  this  mine,  when 
delivered  on  the  dump,  frequently  takes  fire  within  a  few  days  by 
spontaneous  combustion,  and  on  several  occasions  has  set  on  fire  the 
cars  in  which  the  ore  is  transported  to  the  smelter  at  Madera.  A  large 
dump  situated  at  the  south  shaft  has  been  burning  for  some  time,  and 
the  ore  now  presents  the  appearance  of  an  ore-pile  which  has  been  heap- 
roasted  in  the  usual  manner.  In  this  mine  was  observed  one  of  the 
very  few  underhanded  stopes  in  the  State.  The  method  of  working  this 
mine  illustrates  to  a  marked  degree  the  unfortunate  policy  commented 
upon  in  one  of  the  first  paragraphs  of  this  bulletin,  that  of  demanding 
immediate  returns  from  development  of  ore.  There  are  40  miners 
employed  in  the  mine,  15  on  top,  and  60  at  the  smelter,  which  is  located 

near  the  town  of  Madera.     The  smelter  was  not  visited. California 

Copper  Company  of  31  Nassau  Street,  New  York,  owner.  Wm.  Davidson 
of  Daulton,  superintendent. 

Several  copper  mines  are  being  worked  on  Green  Mountain  about  10 
miles  northwest  from  Raymond,  and  there  is  one  near  White  Rock, 
about  15  miles  southwest  of  Mariposa.  These  mines  are  shipping  high- 
grade,  partly  oxidized  ores.     They  were  not  visited. 


INDEX. 


Page. 

Age  of  Calaveras  formation 7 

Age  of  Gold  Belt 7 

Age  of  Mariposa  beds... .-.  8 

Alteration  in  massive  rocks 9 

Alteration  of  basic  rocks  to  steatite 14 

Alteration  of  other  massive  rocks 13 

Alterations    of    tuffs    to    schists    and 

slates -- -.  19 

Altman  Mine 98 

Amador  County 43 

Amador  Queen  No.  1 44 

Amador  Queen  No.  2 44 

Amphibolite  schists ..- 8 

Anderson  Mine  - 44 

Angel  Mine 109 

Ankerite,  Alterations  of,  to  talc 21 

Ankerite,  Probable  origin  of _..  13 

Ankerite  vein,  General  features  of 20 

App  and  Heslep  Mines,  The 131 

Arbona  Mine 129 

Argonaut-Kennedy  vein,  Geology  of  ..  56 

Argonaut  Mill,  Experiments  in 50 

Argonaut  Mine 50 

Argonaut  Slimes  Plant 51 

Azula  Mine 86 

Baliol  Mine 75 

Banded  schists 12 

Bay  State  Mine 85 

Bell  signals 40 

Bell  signals,  California  code  of 40 

Big  Bonanza. 121 

Big  Canon  (see  Oro  Fino) 96 

Black  Hill  (Pumpkin)  Mine 147 

Black  Oak  Mine,  Water  crevice  in 25 

Blue  Jay  and  Yellow  Hammer  Mines.  123 

Bolytho  Mine 120 

Bonanza  Mine.. 147 

Borger  Copper  Mine — 125 

Bovee  Mine 119 

Bown  Mine 129 

Buena  Vista  Mine 91 

Bunker  Hill  Mine 80 

Butte  Mine 45 

Calaveras  County 100 

Calaveras  formation 7 

Calaveras  Mine 123 


Page. 

California  bell  signal  code 40 

California  greenstone 8 

Canvas  plant,  Zeila  Mine 46 

Carson  Creek  Mine  (see  San  Justo) 123 

Centennial  Mine 82 

Center  Mine 91 

Central  Eureka  Mine 64 

Central  Gold  Belt 15 

Central  Lode 14 

Chlorination  works.  Practice  in  Amador 

County 81 

Chlorination  works,  Utica  Mine 118 

Church  Mine 92 

Classification  of  rocks 16 

Clay  slates  at  Gwin  Mine 19 

Clay  slates  of  Mariposa  beds 15 

Clay  slates.  Relation  of  to  veins 15 

Code  of  bell  signals  in  California 40 

Commodore  Mine 103 

Condensation  in  steam  pipes 33 

Connecting  levels 28 

Contact  veins 15 

Contents 2 

Copper  mines  (Ranlett) 87 

Cornish  pumps  compared  with  steam 

pumps - 33 

Cost  of  milling  dumps,  Plymouth  Con. 

Mines 83 

Cost  of  milling  at  Mahoney  Mine 37 

Cost  of  mining 35 

Cost  of  mining  at  Kennedy  Mine 39 

Cost  of  mining  at  Mahoney  Mine 36 

Cost  of  mining  and   milling  at  Gwin 

Mine ...  38 

Cyanide  plant,  Utica  Mine 119 

Cyanide  plant,  Vandalia  Mine 97 

Daulton   Copper   Mine  (see    Ne   Plus 

Ultra) 149 

Demarest  Mine 107 

Diamond  drills.  Use  of 35 

Dikes  in  granite 24 

Dip  of  slate,  schists,  and  veins 15 

Dip   of   veins,    Relation   of,    to    mine 

methods 31 

Direct-acting  steam  pumps  compared 

with  Cornish  pumps 33 

Divisions  of  the  Gold  Belt 14 


152 


INDEX. 


Page. 
Dolomite 1^ 

Dolomitic  vein 13-19 

Dolomitic  vein,  General  structural  fea- 
tures of — 1^ 

Drainage  of  mines - 32 

Drake  Properties  (Ltd.) 121 

Dresiam  (Easton)  Mine - 139 

Dutch  Mme 130 

Dutton,  Capt.  C.  E.,  quoted -.     12 

Eagle-Shawniut  Mine,  The 132 

East  Lode,  The... ---- --14,  21 

El  Dorado  County 88 

El  Dorado  County,  Geology  of -.     88 

Ellen  Taylor  Drift  Mine ---    94 

Ellen  Vannan  Drift  Mine 124 

Emerson  shaft,  Timbering --.     68 

Emerson  shaft  of  Wildman  Mine 68 

Emery  Hydraulic  Mine 124 

Eruptive  rocks  at  Logtown 89 

Esperanza  Mine -- - 123 

Eureka  Slate  Quarry.  - 99 

Experimental  work,  Keystone  Mill 79 

Fairbanks,  H.  W.,  Determinations  by.    16 

Fault  in  the  Keystone  Mine 77 

Fault  in  the  Princeton  Mine 147 

Fellowcraft  (Bode,  or  Veritas) 105 

Filling,  Necessity  of  prompt 32 

Filling  of  stopes 31 

Filling,  Where  obtained 31 

Ford  Mine 107 

Formation  of  mineral  veins 22 

Fortuna  Mine.. 98 

Free  American  Mine 76 

Fremont  Mine 80 

French  Hill  Quartz  Mine 125 

Gentle  Annie  Mine 94 

Geology  of  Argonaut-Kennedy  vein  ...    56 

Geolog5' of  Gold  Belt 7 

Geology  of  Keystone  Mine. 77 

Geology  of  Pine  Tree-Josephine  Mine.  145 

Geology  of  the  Vandalia  Mine. 97 

Geology  of  Wildman-Mahoney  Mine..     65 

German  Mine 90 

German  Mine,  Peculiar  intrusions  in..    90 

Gold  Cliff  Mine Ill 

Gold-bearing  zone,  A 140 

Gold  Belt,  Age  of 7 

Gold  Belt,  Central 15 

Gold  Belt,  Geology  of 7 

Gold  Belt,  Divisionsof 14 

Golden  Rule  Mine  (see  Jumper) 131 

Gold  in  granite 24 

Gold  in  talc 86 

Goldwin  Mines 138 

Gopher-Boulder  Mine 98 


Page. 

Gover  Mine  (see  Fremont) 80 

Gowanus  Mine 85 

Granite  areas ..   21 

Granite,  Dikes  in  . 24 

Granite,  Gold  in 24 

Granite,  Ores  in 22 

Granite,  Veins  in 22 

Great  Western  Mine. 120 

Greek  Mine 123 

Green  Mountain  Mine  (hydraulic  and 

drift).. 124 

Green  Mountain  Copper  Mines 150 

Greenstones  of    California    similar  to 

Michigan ... 8 

Griffith  Mine.... 92 

Grizzly  Mine 139 

Gwin  Mill,  Practice  at 103 

Gwin  Mine. 100 

Gwin  Mine,  Clay  slates  in 19 

Gwin  Mine,  Cost  of  mining  and  milling    38 

Gwin  Mine,  Method  of  mining  at. 100 

Gwin  Mine,  Method  of  timbering  at 102 

Harris  Mine  (see  Big  Bonanza)... 121 

Harvard  (Whisky  Hill)  Mines. 130 

Hayward  Hydraulic  Mine 99 

Hector  or  Mahoney  Mill 71 

Heslep  Mine  (see  App) 131 

Illinois  Mine 107 

Illustrations,  List  of 3 

Intermediate  levels 30 

Ivanhoe  Mine 84 

Jackass  Hill 129 

Jack  Hanley  Mine 99 

Josephine  Mine,  Geology  of ..  144 

Josephine  Mine,  The 143 

Jumper  group  of  mines... 131 

Kennedy  Mill 54 

Kennedy-Argonaut  vein.  Distribution 

of  ore-shoots  in 53 

Kennedy  Mine 52 

Kennedy  Mine,  Geology  of  vein  in .56 

Kennedy  Mine,  New  vertical  shaft 53 

Kennedy  Slimes  Plant 55 

Keystone  Mill 79 

Keystone  Mine 77 

Keystone  Mine,  Geological  structure  of  77 

Kirkwood  Mine 45 

Kretcher  Vein  (see  Bay  State)..     85 

Larkin  Mine 93 

Last  Chance  Mine 122 

Last  Chance  Mine  (El  Dorado  County).    91 

Letter  of  Transmittal 4 

Lightner  Mill 109 


INDEX. 


153 


Page. 

Lightner  Mine  (at  Angels) - 109 

Lightner  Mine  (at  Copperopolis) 126 

Lincoln  Mine 72 

Lincoln  Mine,  Fault  in 73 

List  of  Illustrations 3 

Lodi  Mine  (see  Sheep  Ranch) 104 

Longfellow  Mine - 139 

Mack  Mine 140 

Madeline  Mine 91 

Madera  County 148 

Mahonej'  Mill,  Cost  of  milling  at 37 

Mahoney  (or  Hector)  Mill,  Practice  in.  71 

Mahoney  Mine,  Cost  of  mining  at 36 

Mahoney  Mine,  Geology  of 65 

Manila  ropes  in  Ranlett  Copper  Mine.  87 

Marguerite  Mine 93 

Mariposa  beds,  Position  of 8 

Mariposa  County  .._ 142 

Mariposa  Estate,  Mining  machinery  on    40 

Mariposa  Mine 142 

Mariposite 13 

Mary  Harrison  Mine 146 

Massive  rocks,  Alteration  of 9 

Melones  Consolidated  Mine 121 

Merced  Gold  Mining  Company 146 

Metamorphic  rock  and  schist... 8 

Metamorphism  of  tuffs 12 

Methods  of  mining 26 

Mill  practice  at  Utica-Stickle  Mine 111 

Mine  bell  signals 40 

Mineral  veins.  Formation  of 22 

Mining,  Cost  of 35 

Mining,  Cost  of  at  Kennedy  Mine 39 

Mining,  Cost  of  at  Gwin  Mine 38 

Mining,  Cost  of  by  Wildman  Co. 86 

Mining  machinery. 39 

Mining  machinery  on  Mariposa  Estate  40 

Minnehaha  Mine 95 

Monitor  Mine 98 

Montauk  Gold  Mining  Co.  (see  Zant- 

graf). 99 

Montezuma  Mine 91 

Mother  Lode 14 

Murphy  Mine.. 147 

Mutual  Mine 74 

Nashville  Mine 91 

Ne  Plus  Ultra  Copper  Mine 149 

New  York  Mine  (see  Anderson  Mine)..    44 

Noonday  Mine  (copper)... 91 

North  Star  Drift  Mine 124 

Norwegian  Mine 129 

Nugget  Mine 86 

Oneida  Mine 60 

Oneida  new  shaft,  Formations  in 62 

Ores  in  granite 22 

11 — MB 


Page. 
Ore-shoots  in  Kennedy-Argonaut  vein, 

Distribution  of 53 

Origin  of  ankerite 13 

Oro  Fino  Mine.- 96 

Pacific  Mine,  Placerville 13 

Peerless  Mine. 45 

Perlina  Mine  _ 120 

Philadelphia  Mine 84 

Phoenix    Reduction  Works   (chlorina- 

tion) 81 

Pine  Tree  Mine 145 

Pine  Tree  Mine,  Fault  in 145 

Pine  Tree  Mine,  Geology  of 146 

Pioneer  Mine 83 

Pitted  slates 15 

Placerville  Slate  Quarry 94 

Plymouth  Consolidated  Mine,  Milling 

dumps  of 82 

Pocahontas  Mine,  Amador  County 83 

Pocahontas  Mine,  El  Dorado  County..    95 

Pocket  Mines  (see  Jackass  Hill) 129 

Potazuba 76 

Princeton  Mine,  The 148 

Queen  Mine 87 

Ranlett  Copper  Mine 87 

Rawhide  Mine 129 

Red  Cloud  Mine 85 

Reduction  Works,  Phoenix 81 

Relief  Mine 121 

Renshaw,  J.,  on  pumps 33 

Revera  Mine 94 

Rex  Mine,  The.. 148 

Rex  Mine,  Fault  in  the 148 

Rhetta  Mine. 86 

Ribbon  Rock  and  Tin  Cup  Mines 94 

Ritter  Mine 123 

Rocks,  Classification  and  description  of    16 

Rocks,  Eruptive,  at  Logtown... 89 

Roma  and  Sierra  Blanca  Mines 146 

Royal  Consolidated  Gold  Mine 126 

Royal  Mill,  The 127 

San  Domingo  Hydraulic  (Jupiter)  Mine  125 

San  Justo  (Carson  Creek)  Mine 123 

Satellite  Copper  Mine 125 

Schists,  Banded 12 

Schists  and  metamorphic  rocks... 8 

Selby  Mine.- 93 

Shaft,  Arrangements  to  ventilate 34 

Shenandoah  Mine _.     84 

Sheep  Ranch  Mine 104 

Sierra  Blanca  and  Roma  Mines 146 

Sierra  Lode -..  15 

Sills,  LTse  of  in  timbering 30 

Slate  Quarry,  Eureka 99 


154 


INDEX. 


Page. 

Slate  Quarry,  Placerville 94 

South  Eureka  Mine -..  63 

South  Keystone  Con.  Mine 77 

South  Spring  Hill  Mine 11 

Spagnoli  Mine 45 

Spanish  Dry  Diggings 98 

Starlight  Mine 95 

Steam  pipes,  Condensation  in 33 

Steatite 14 

Steam  pumps  compared  with  Cornish 

pumps 33 

St.  Lawrence  Mine. 120 

tStopes,  Superficial  area  of 30 

Structural  geology  of  the  Gold  Belt  ...  7 

Swelling  ground 27 

Talc  derived  from  alteration  of  ankerite    21 

Talc  mines.- 86 

Timbering    Emerson   shaft,   Wildman 

Mine 68 

Timbering  in  mines 30 

Timbering  in  new  shaft,  Kennedy  Mine    54 

Tin  Cup  and  Ribbon  Rock  Mines 94 

Transition  rocks 13 

Treadwell  &  Guliana  Mine 76 

Tuffs  altered  to  schists  and  slates 19 

TuUoch  Mine 121 

Tuolumne  County 128 

Umatilla  Drift  Mine 94 

Union  and  Keystone  Copper  Mines 126 

Union  Mine _ 92 

Utah,  Eruption  on  high  plateau  of 12 


Page. 

Utica  Chlorination  Works 118 

Utica  Cyanide  Plant 119 

Utica-Stickle  Mill,  Practice  in Ill 

Utica-Stickle  Mine 110 

Vandalia  Mine 96 

Vandalia  Mine  Cyanide  Plant 97 

Veins,  Formation  of  .- 22 

Veins,  in  granite 22 

Ventilation  in  shafts 34 

Veritas  Mine  (Bode,  or  Fellowcraft) ...  105 

Walls,  Gangways  in. 27 

Walls  of  veins,  Mineralization  of 26 

Water  in  mines.  Relation  of  to  ore 25 

Waterjacket  smelter  at  Ranlett 87 

Whisky  Hill  Mines  (see  Harvard) 130 

White  Rock  Copper  Mines 150 

Wildman  Co.,  Cost  of  mining  by 36 

Wildman  Co.,  Cost-sheet  excludes  1899- 

1900 39 

Wildman  Mill - 71 

Wildman-Mahoney  Mine 65 

Wildman  Mine,  New  vertical  shaft  at..  68 

Williams,  G.  H.,  quoted 9 

Yosemite  Hydraulic  Mine 147 

Zantgraf  Mine 99 

Zeila  Canvas  Plant,  The 46 

Zeila  Mill,  Experiments  in 46 

Zeila  Mine 45 


